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Most people who attend primary school in the United States and in other industrialized nations experience puretone* testing firsthand as a method to screen for hearing loss. Puretone threshold testing is seen in films, such as Woody Allen’s award-winning movie Hannah and Her Sisters or the film Wind Talkers. These casual experiences with audiology may give lay people the false impression that audiology is a narrow profession.
在美国和其他工业化国家，大多数上小学的人都经历过纯音测试，而纯音测试是一种筛选听力损失的方法。纯音阈值测试可以在电影看到，比如伍迪·艾伦的获奖电影《汉娜和她的姐妹们》或者电影《风语者》。这些与听力学有关的偶然经历可能会给外行人一个错误的印象，即听力学是一个狭窄的职业。
*The use of the compound noun “puretone” is the editor’s choice for consistency purposes.
复合名词“puretone”的使用是编辑出于一致性目的而选择的。
Most audiologists would likely agree that puretone (PT) thresholds represent a key component of the assessment battery. Proper administration and interpretation of PT threshold tests require considerable knowledge, as it is not always simple and straightforward. The goal of this chapter is to introduce readers to the complexity of PT threshold testing, as well as to provide clinicians with a reference for clinical applications.
大多数听力学家可能会同意纯音（PT）阈值是评估组块的一个关键组成部分。纯音阈值测试的正确使用和解释需要大量的知识，因为它并不总是简单和直接的。本章的目的是向读者介绍纯音阈值测试的复杂性，并为临床医师提供临床应用参考。
WHAT ARE PURETONES AND HOW ARE THEY SPECIFIED?
什么是纯音，它们是如何定义的？
PT thresholds represent the lowest level of response to a tonal stimulus. Puretones are the simplest of sounds described by their frequency, amplitude, phase, and duration. The most important of these characteristics for puretone audiometry are frequency and amplitude (or intensity level).
纯音阈值是对音调刺激最低响应级别的表示。纯音是根据频率、振幅、相位和持续时间来描述的最简单的声音。这些特征中对于纯音测听来说最重要的是频率和振幅（或强度级别）。
Puretone frequency is perceived as pitch, the characteristic of sound that determines its position on a musical scale. Young people with normal hearing are able to perceive frequencies between 20 and 20,000 Hz. Human hearing is more sensitive (better) in the range of frequencies between 500 and 8,000 Hz than it is at either extreme of the audible range of frequencies. Conventional puretone audiometry typically assesses thresholds for frequencies between 250 (or 125) and 8,000 Hz. The frequency range for conventional audiometry is very similar to the range of frequencies (100 to 6,000 Hz) that is important for speech understanding (French and Steinberg, 1947).
纯音频率被视为音高（音调），声音的特性决定了它在音阶中的位置。听力正常的年轻人能够感知20到20000赫兹之间的频率。人类的听觉在500到8000赫兹的频率范围内比在可听频率范围的任一极端都更灵敏（更好）。传统的纯音测听通常评估频率在250（或125）到8000赫兹之间的阈值。传统测听的频率范围非常相似对语音理解很重要的频率范围（100到6000 Hz）（French and Steinberg, 1947）。
Puretone amplitude or level is usually quantified in decibels. Decibels (dB) represent the logarithm of a ratio of two values; the term is meaningless without a reference. Two commonly used decibel scales are sound pressure level (SPL) and hearing level (HL). The reference level for dB SPL is 20 μPa, a pressure value. This reference value for SPL was selected to correspond to the faintest pressure that is audible in the frequency region where hearing is most sensitive. The frequency is not specified in the reference level for dB SPL; all sounds expressed in units of dB SPL share the same reference of 20 μPa. The SPL scale is frequently used in audiology to compare the level of speech or other sounds at different frequencies. Such comparisons are critical for prescribing and evaluating hearing aids. HL, a second decibel scale, is used to plot an audiogram, the accepted clinical representation of puretone thresholds as a function of frequency. The reference for dB HL is the median threshold for a particular frequency for young adults with no history of ear problems. Unlike dB SPL, the zero reference level for dB HL varies with frequency, because humans have more sensitive hearing at some frequencies than others. Because the reference is normal human hearing, thresholds that deviate from 0 dB HL at any frequency show how much one’s hearing deviates from this normal value.
纯音的振幅或音量通常用分贝表示。分贝（dB）表示两个值之比的对数；没有参考，这个术语就没有意义。两种常用的分贝标度是声压级（SPL）和听力级（HL）。dB SPL的参考音量是20μPa，一个压力值。SPL的这个参考值是根据听觉最敏感的频率区域所能听到的最微弱的压力来选择的。dB SPL参考音量未指定频率；所有以dB SPL为单位表示的声音共享相同的参考20μPa。SPL测量在听力学中经常用来比较不同频率下的语音或其他声音的水平。这种比较对于开处方和评估助听器至关重要。HL是第二种分贝标度，用于绘制听力图，纯音阈值作为频率函数的公认临床表现。dB HL的参考值是一个特定频率的中值阈值，适用于没有耳部病史的年轻人。与dB SPL不同，dB HL的零参考水平随频率变化，因为人类在某些频率下的听力比其他频率更灵敏。因为参考的是正常人的听力，在任何频率上偏离0 dB HL的阈值显示了一个人的听力偏离这个正常值的程度。
Figure 3.1 illustrates thresholds displayed in dB SPL and dB HL. The left panel shows hearing thresholds plotted in dB SPL as a function of frequency. Thresholds plotted in this way constitute a minimum audibility curve. The right panel shows a conventional audiogram plotted in dB HL. Note that on the dB SPL scale, larger decibel values are plotted higher on the graph. By contrast, larger values in dB HL are plotted lower on the audiogram. To illustrate the relationship between dB SPL and dB HL, the reference values for 0 dB HL (average normal hearing) for a specific earphone are plotted in dB SPL as a solid line. Illustrated with a dashed line on these same two figures are the thresholds for a person with a high-frequency hearing loss. Note in the figure on the left that the separation between the solid line and the dashed line represents values for dB HL on the audiogram.
图3.1显示了以dB SPL和dB HL显示的阈值。左图显示以dB SPL绘制的听力阈值作为频率的函数。以这种方式绘制的阈值构成最小可听曲线。右图显示了以dB HL绘制的传统听力图。请注意，在dB SPL标度上，较大的分贝值在图表上绘制得更高。相比之下，在听力图上较大的dB HL值被绘制得较低。 为了说明dB SPL和dB HL之间的关系，将特定耳机的0 dB HL（平均正常听力）的dB SPL参考值绘制为实线。在这两个图中用虚线表示的是高频听力损失的人的阈值。请注意，左侧图中实线和虚线之间的间隔表示听力图上dB HL的值。
The reader might be wondering why audiologists use puretones at specific frequencies when the most meaningful stimulus is speech. Two important reasons are that PT thresholds provide information about the type of hearing loss, as well as quantify frequency-specific threshold elevations that result from damage to the auditory system.
读者可能想知道，为什么听力学专家在特定频率使用纯音，而最有意义的刺激是语音。 两个重要原因是纯音阈值提供了有关听力损失类型的信息，并且量化了由听觉系统受损导致的特定频率阈值升高多少。
PT thresholds provide quantification of amount of loss due to problems with the outer and middle ear (the conductive system) separately from the cochlea and the auditory nerve (the sensory/neural system). This distinction helps in the diagnosis and guides audiologists and physicians with important details for providing treatment strategies.
纯音阈值提供了外耳和中耳（传导系统）不同于耳蜗和听神经（感音/神经系统）所导致的损失量的量化。这种区别在诊断和指导方面有助于为听力师和医生提供有关治疗策略的重要细节。
Damage to the auditory system often results in a loss of sensitivity that is frequency specific. For instance, changes in the stiffness and mass properties of the middle ear affect the relative amount of loss in the low and high frequencies (Johanson, 1948). For air-conduction thresholds, an increase in stiffness results in a greater low-frequency loss, whereas an increase in mass results in a greater loss in the high frequencies. Thresholds for puretones (or other narrowband sounds) also provide us with diagnostic information about the integrity of different channels in the sensory/neural pathway. The auditory system is organized tonotopically (i.e., a frequency-to-place mapping) from the cochlea to the cortex. The tonotopic organization of the cochlea is a result of the frequency tuning of the basilar membrane, with high frequencies represented at the basal end and low frequencies at the apical end. Damage to sensory cells of the cochlea at a specific place along the basilar membrane can result in a loss of hearing that corresponds to the frequencies coded by that place. For this reason, PT threshold tests provide details that would otherwise remain unknown if a broadband stimulus such as speech were used.
听觉系统的损伤通常会导致特定频率的灵敏度下降。例如，中耳硬度和质量特性的变化会影响低频和高频的相对损失量（Johanson, 1948）。对于空气传导阈值，硬度的增加导致更大的低频损耗，而质量的增加导致更大的高频损耗。纯音（或其他窄带声音）的阈值也为我们提供了关于感音/神经通路中不同通道完整性的诊断信息。听觉系统是从耳蜗到皮质的以拓扑方式组织的（即，频率到位置的映射）。耳蜗的拓扑组织是基底膜频率调谐的结果，在基底端表现为高频，在顶端表现为低频。耳蜗基底膜上某一特定位置的感觉细胞受损，会导致与该位置编码频率相对应的听力的丧失。由于这个原因，纯音阈值测试提供了一些细节，如果使用语音等宽带刺激，这些细节将不得而知。
In addition to providing audiologists with critical diagnostic information about the amount and type of loss, PT thresholds find applications (1) for estimating the degree of handicap, (2) as a baseline measure for hearing conservation programs, (3) for monitoring changes in hearing following treatment or progression of a disease process, (4) for screening for hearing loss, (5) for determining candidacy for a hearing aid or a cochlear implant, and (6) for selecting the frequency-gain characteristics of a hearing aid. PT thresholds also provide a reference level for presentation of suprathreshold speech testing and for the meaningful interpretation of other audiologic tests, such as evoked otoacoustic emissions and acoustic reflex thresholds. PT thresholds are also used to assess the functional attenuation of hearing protection devices.
除了向听力师提供关于损失数量和类型的关键诊断信息之外，纯音阈值还应用于：（1）评估残障的程度，（2）作为听力保护计划基线测量，（3）用于监测治疗或疾病进展后的听力变化，（4）听力损失的筛查，（5）确定助听器或人工耳蜗的候选资格，（6）选择助听器的频率增益特性。纯音阈值还为阈上语音测试的呈现提供了参考，并为其他听力测试（如诱发耳声发射和声反射阈值）的有意义解释提供了参考。纯音阈值也被用来评估听力保护装置功能的衰减。
TUNING FORK TESTS
音叉试验
A struck tuning fork produces a sustained puretone that decays in level over time. Unlike an audiometer, tuning forks cannot present a calibrated signal level to a listener’s ear. Despite this shortcoming, tuning fork tests provide qualitative information that can help determine whether a hearing loss is conductive or sensory/neural. Tuning fork tests are promoted by some as an important supplement to puretone audiometry. In a recently published book, otologists are advised to include tuning fork tests as an integral part of the physical examination for conductive hearing loss(Torres and Backous, 2010).
被敲击的音叉产生持续的纯音，其音量会随着时间的推移而衰减。与听力计不同，音叉不能向听者耳朵提供经过校准的信号。尽管有这个缺点，音叉测试提供的定性的信息可以帮助确定听力损失是传导性的还是感音/神经性的。一些人提倡使用音叉测试作为纯音测听的重要补充。在最近出版的一本书中，耳科医生被建议将音叉测试纳入传导性听力损失的体检中（Torres and Backous, 2010）。
The two best known tuning fork tests are the Weber and Rinne. Judgments about the type of hearing loss are made by comparing the pattern of results on both tests. Air conduction (AC) is tested by holding the tuning fork at the opening of the ear canal, and bone conduction (BC) is tested by placing the tuning fork on the mastoid process (the bony area behind the pinna) or on the forehead or incisors (British Society of Audiology, 1987). For the Weber test, a client judges whether sound is perceived in one or both ears when the tuning fork is placed on the forehead. For the Rinne test, the client judges whether sound is louder when presented by AC or by BC. Ideally, conductive hearing losses produce a pattern of responses that is uniquely different from the one for sensory/neural hearing losses. In the Weber, the sound is lateralized to the poorer ear with a conductive loss and to the better ear for a sensory/neural loss. In the Rinne, the sound is louder by BC in a conductive loss and by AC with a sensory/neural loss.
最著名的两个音叉试验是韦伯试验和林纳试验。通过比较两种测试结果来判断听力损失的类型。空气传导（AC）通过将音叉放在耳道口进行测试，骨传导（BC）通过将音叉放在乳突（耳廓后的骨质区域）或前额或门牙上进行测试（英国听力学学会，1987）。在韦伯测试中，当音叉放在前额上时，受试者判断是单耳还是双耳感知到声音。在林纳试验中，受试者判断是AC还是BC感知的声音更大。理想情况下，传导性听力损失会产生一种不同于感官/神经性听力损失的反应模式。在韦伯试验中，在传导性聋中声音偏向差耳，在感音/神经性聋中偏向好耳。林纳试验中，在传导性损失下，骨导感知的声音更大，在感觉/神经性损失下，气导感知的声音更大。
Some recommend tuning fork tests to check the validity of audiograms (Gabbard and Uhler, 2005) or to confirm the audiogram before conducting ear surgery (Sheehy et al., 1971). However, it is important to recognize that tuning fork tests administered to people with known conductive losses have shown that these procedures are often inaccurate (Browning, 1987; Snyder, 1989). Although only about 5% of people with normal hearing or sensory/neural losses are falsely identified as having conductive losses with the Rinne test, this test misses many people with significant conductive losses (Browning, 1987), including 50% of losses that have 20-dB air–bone gaps. The Weber test fares equally poorly. Browning (1987) reports that a majority of children with conductive losses give inappropriate responses on the Weber test. From these and other studies, one must conclude that tuning fork tests are not a replacement or even a supplement to audiometry. Audiometry is capable of identifying nearly 100% of air–bone gaps, as small as 15 dB.
有人建议使用音叉试验来检查听力图的有效性（Gabbard and Uhler, 2005），或者在进行耳外科手术前确认听力图的有效性（Sheehy et al.， 1971）。然而，重要的是要认识到，对已知传导性损伤的人进行的音叉试验表明，这些往往是不准确的（Browning, 1987;斯奈德,1989）。虽然只有大约5%的听力正常或感觉/神经损失的人通过林纳试验被错误地识别为传导性损失，但是这个测试遗漏了许多有显著传导性损失的人（Browning, 1987），包括其中50%的有20分贝气骨间隙的损失。韦伯试验的表现同样糟糕。Browning（1987）报告说，在韦伯试验中，大多数有传导性损失的儿童给出了不恰当的反应。从这些研究和其他研究中，我们必须得出这样的结论：音叉试验不是听力测试的替代品，甚至不是它的补充。听力测定能够识别几乎100%的气骨间隙，最小可达15分贝。
PURETONE AUDIOMETRY
纯音测听
Audiometers are used to make quantitative measures of AC and BC PT thresholds. AC thresholds assess the entire auditory pathway and are usually measured using earphones. When sound is delivered by an earphone, the hearing sensitivity can be assessed in each ear separately. BC thresholds are measured by placing a vibrator on the skull, with each ear assessed separately, usually by applying masking noise to the nontest ear. The goal of BC testing is to stimulate the cochlea directly, thus bypassing the outer and middle ears. A comparison of AC and BC thresholds provides separate estimates of the status of the conductive and sensory/neural systems. If thresholds are elevated equally for sounds presented by AC and BC, then the outer and middle ear are not contributing to a hearing loss. By contrast, if thresholds are poorer by AC than by BC, then the source of at least some of the loss is the outer or middle ear. Figure 3.2 illustrates the AC and BC pathways and how hearing thresholds are typically affected by damage to these structures. See Chapter 4 for a complete review of BC assessment.
听力计用于定量测量空气传导和骨传导纯音阈值。空气传导阈值评估整个听觉通路，通常使用耳机测量。当通过耳机发出声音时，可以分别在每只耳朵中评估听觉灵敏度。骨传导阈值通过在颅骨上放置振动器来测量，每个耳朵单独评估，通常是通过对非测试耳施加掩蔽噪声来测量。骨传导测试的目标是直接刺激耳蜗，从而绕过外耳和中耳。空气传导和骨传导阈值的比较提供了对传导和感音/神经系统状态的分别评估。如果空气传导和骨传导所呈现的声音阈值同等升高，则外耳和中耳不会导致听力损失。相反，如果空气传导的阈值比骨传导的阈值更差，那么至少一些损失来自外耳或中耳。图3.2显示了空气传导和骨传导通路以及听力阈值如何受到这些结构损伤的影响。有关骨传导评估的完整回顾，请参见第4章。
FIGURE 3.2 Conductive and sensory/ neural pathways. (Adapted from Martin (1994))
图3.2传导通路和感觉/神经通路。（改编自Martin (1994)）
Equipment
设备
AUDIOMETERS
听力计
Puretones are generated within an audiometer. Audiometers have the ability to select tonal frequency and intensity level and to route tones to the left or right earphone. All audiometers also have an interrupter switch that presents the stimulus to the examinee. The American National Standards Institute (ANSI) Specification for Audiometers (ANSI, 2010) describes four types of audiometers, with Type 1 having the most features and Type 4 having the fewest features. A Type 1 audiometer is a full-featured diagnostic audiometer. A Type 1 audiometer has earphones, bone vibrator, loud speakers, masking noise, and other features. A Type 4 audiometer is simply a screening device with earphones, but none of the other special features.
纯音是在听力计中产生的。听力计能够选择音调频率和强度级别，并将音调传送到左耳机或右耳机。所有听力计也有一个断续开关，向受检者提供刺激。美国国家标准协会（ANSI）中听力计的规范（ANSI，2010年）描述了四种类型的听力计，类型1功能最多，类型4功能最少。1型听力计是一种功能齐全的诊断听力计。1型听力计具有耳机、骨振动器、扬声器、掩蔽噪音和其他功能。4型听力计只是一种带有耳机的筛选设备，不具有其他特殊功能。
Type 1 (full-featured, diagnostic audiometer) has the ability to assess puretone AC thresholds for frequencies ranging from 125 to 8,000 Hz and BC thresholds for frequencies ranging from 250 to 6,000 Hz. If an audiometer has extended high-frequency capability, air-conduction thresholds can be extended to 16,000 Hz. Maximum output levels for AC testing are as high as 120 dB HL for frequencies where hearing thresholds are most sensitive. By contrast, distortion produced by bone oscillators at high intensities limits maximum output levels for BC thresholds to values nearly 50 dB lower than those for AC thresholds for the same frequency.
类型1（功能齐全的诊断听力计）能够评估125至8000 Hz频率的纯音气导阈值和250至6000 Hz频率的骨导阈值。如果听力计具有扩展的高频能力，则气导阈值可以扩展到16,000 Hz。 在听力阈值最敏感的频率范围内，气导测试的最大输出水平高达120 dB HL。相比之下，骨振动器在高强度下产生的失真将骨导阈值的最大输出限制在比相同频率下气导阈值的输出低近50 dB。
TRANSDUCERS
换能器
Earphones
耳机
Earphones are generally used to test puretone AC thresholds. A pair of supra-aural earphones is illustrated in Figure 3.3. For decades, supra-aural earphones, ones in which the cushion rests on the pinna, were the only choice for clinical audiology. The popularity of supra-aural phones was mainly due to their ease of calibration and the lack of other types of commercially available earphones. In the past few years, insert earphones and circumaural earphones have become available and provide some useful applications for puretone assessment.
耳机通常用于测试纯音气导阈值。图3.3显示了一对压耳式耳机。几十年来，压耳式耳机（耳垫放在耳廓上）是临床听力学的唯一选择。压耳式耳机之所以受欢迎，主要是因为它们易于校准，而且缺乏可商用的其他类型耳机。在过去的几年中，插入式耳机和耳罩式耳机已经面世，并应用于纯音评估。
图3.3 TDH-49型，一种压耳式耳机
Insert earphones are coupled to the ear by placing a probe tip, typically a foam plug, into the ear canal. The commercially available model that has a standardized calibration method for audiology is the Etymotic model ER-3A, which is illustrated in Figure 3.4. These earphones have gained popularity in the past few years because they offer distinct advantages over supra-aural earphones. One major advantage is that insert earphones yield higher levels of interaural attenuation than supra-aural earphones (Killion and Villchur, 1989). Interaural attenuation represents the decibel reduction of a sound as it crosses the head from the test ear to the nontest ear. The average increase in interaural attenuation is roughly 20 dB. This reduces the need for masking the nontest ear and decreases the number of masking dilemmas, situations for which thresholds cannot be assessed, because the presentation level of the masking noise is possibly too high. (See Chapter 6 for a comprehensive review of masking.) Another important advantage of insert earphones over supra-aural earphones is lower test–retest variability for thresholds obtained at 6 and 8 kHz; variability for other frequencies is comparable. Given that thresholds for 6 and 8 kHz are important for documenting changes in hearing due to noise exposure and for identifying acoustic tumors, lower variability should increase the diagnostic precision. A third advantage that insert earphones offer is elimination of collapsed ear canals (Killion and Villchur, 1989). In about 4% of clients, supra-aural earphones cause the ear canal to narrow or be closed off entirely when the cushion presses against the pinna, collapsing the ear canal (Lynne, 1969), resulting in false hearing thresholds, usually in the high frequencies (Figure 3.5) (Ventry et al., 1961). Because insert earphones keep the ear canal open, collapsed canals are eliminated. A fourth advantage of insert earphones is that they can be easily used with infants and toddlers who cannot or will not tolerate supra-aural earphones. A fifth advantage of insert earphones is the option of conducting middle-ear testing and otoacoustic emission testing without changing the earphones; some recently introduced diagnostic instruments use this approach. Although insert earphones offer a hygienic advantage over supra-aural earphones, because the foam tips that are placed into a client’s ear canal are disposable, the replacement cost of those tips is prohibitive for many applications. In addition to higher costs, insert earphones also yield errant thresholds in persons with eardrum perforations, including pressure-equalization tubes (Voss et al., 2000). (See Figure 3.12 for additional information about perforations.) Insert earphones also have maximum output levels that are lower than those produced by supra-aural earphones for some frequencies. Because of these differences, many diagnostic clinics keep both earphone types on hand and switch between them depending on the application.
插入式耳机通过将探头尖端（通常是泡沫塞）插入耳道与耳朵相连。通过听力学标准化校准方法的市售模型是etymotic模型ER-3a，如图3.4所示。这种耳机在过去几年里很受欢迎，因为它们比压耳式耳机有明显的优势。一个主要优点是插入式耳机比压耳式耳机具有更高的耳间衰减（Killion和Villchur，1989年）。耳间衰减代表声音从测试耳穿过头部到非测试耳时的分贝衰减。耳间衰减平均增加约20dB。这减少了掩蔽非测试耳朵的需求，并减少了掩蔽困境的数量，这种困境是无法评估阈值的情况，因为掩蔽噪声程度可能太高。（有关掩蔽的全面回顾，请参阅第6章。）。与压耳式耳机相比，插入式耳机的另一个重要优点是，在6k和8 kHz处测得的阈值的复测变异性较低；其他频率的变异性的可比较的。鉴于6和8 kHz的阈值对于记录噪声暴露引起的听力变化和识别听神经瘤非常重要，较低的变异性可提高诊断精度。插入耳机提供的第三个优点是消除耳道塌陷（Killion和Villchur，1989年）。在约4%的试验者中，当耳垫压在耳廓上时，压耳式耳机会导致耳道狭窄或完全关闭，使耳道塌陷（Lynne，1969），从而导致错误的听力阈值，通常为高频（图3.5）（Ventryet al.，1961）。由于插入耳机使耳道保持开放，从而消除了耳道塌陷。插入式耳机的第四个优点是，它可以很容易用于不能或不愿忍受压耳式耳机的婴幼儿。插入式耳机的第五个优点是可以在不更换耳机的情况下进行中耳测试和耳声发射测试；最近推出的一些诊断仪器使用这种方法。尽管插入式耳机与压耳式耳机相比更卫生，但由于放置在受试者耳道中的泡沫耳塞是一次性的，更换这些耳塞的成本对于许多机构来说是难以承受的。除了较高的费用外，插入式耳机还会对鼓膜穿孔的人产生错误的阈值，包括压力平衡管（Voss等人，2000年）。（有关穿孔的更多息，请参见图3.12。）在插入式耳机的最大输出也低于压耳式耳机在某些频率下的最大输出。由于这些差异，许多诊所保留了这两种耳机类型，并根据不同的应用情况在它们之间切换。
图3.4 Etymotic型号ER-3A插入式耳机
Circumaural earphones, a third type, have cushions that encircle the pinna. ANSI (2010) describes reference equivalent threshold SPL values (SPL values corresponding to 0 dB HL) for Sennheiser model HDA200 and Koss model HV/1A earphones. These earphones and the Etymotic ER-2 insert earphones are the only ones in the current standard that have reference values covering the extended high frequencies (8 to 20 kHz).
耳罩式耳机是第三种类型，具有环绕耳廓的垫子。 ANSI（2010）描述了Sennheiser型号HDA200和Koss型号HV / 1A耳机的参考等效阈值SPL值（对应于0dB HL的SPL值）。 这些耳机和Etymotic ER-2插入式耳机是目前标准中唯一具有覆盖扩展高频（8k至20 kHz）参考值的耳机。
Current standards for earphone calibration specify the level based on measures obtained with the earphone attached to an acoustic coupler or artificial ear. These couplers are designed to approximate the ear canal volume of an average person. Given that some clients (e.g., infants) have very small or very large ear canals (e.g., some postsurgical clients and persons with perforated eardrums), coupler measures may produce erroneous results, regardless of the earphone type (Voss et al., 2000; Voss and Herman, 2005). For these cases, measuring the SPL at the eardrum to specify the level presented to an individual patient would improve the accuracy of hearing thresholds. The probetube microphones necessary for these types of measures already exist, and hopefully, this technology will become routinely available for use in diagnostic audiometers (see Scheperle et al., 2011 for a discussion of calibration in the ear canal).
当前的耳机校准标准是根据耳机连接到声音耦合器或仿真耳上所获得的测量值来规定的。这些耦合器被设计成近似于一个普通人的耳道容积。考虑到一些受试者的耳道非常小（例如婴儿）或非常大（例如一些术后病人和耳膜穿孔的人），无论何种类型的耳机，耦合器测量都可能产生错误的结果（Voss等，2000; Voss和Herman，2005）。对于这些情况，测量鼓膜处给予个体患者的SPL将提高听力阈值的准确性。这类措施所需的探头麦克风已经存在，希望这项技术可以常规地用于诊断听力计（关于耳道校准的讨论，参见Scheperle等，2011）
Speakers
扬声器
AC thresholds can be measured using speakers as the transducer. Thresholds so obtained are known as sound-field thresholds. Sound-field thresholds are unable to provide ear-specific sensitivity estimates. In cases of unilateral hearing losses, the listener’s better ear determines threshold. This limitation and others dealing with control over stimulus level greatly limit clinical applications involving sound-field thresholds. Applications for sound-field thresholds are screening infant hearing or demonstrating to the parents their child’s hearing ability. Sound-field thresholds may also be desirable for a person wearing a hearing aid or cochlear implant.
气导阈值可以用扬声器作为换能器来测量。这样获得的阈值称为声场阈值。声场阈值无法提供特定耳的灵敏度评估。在单侧听力丧失的情况下，听者较好的耳朵决定了阈值。这种局限性和有关其他刺激程度的控制极大地限制了涉及声场阈值的临床应用。声场阈值应用于筛查婴儿听力，或向父母展示其孩子的听力能力。对于配戴助听器或人工耳蜗的人来说，声场阈值也是可取的。
In sound-field threshold measures, the orientation of the listener to the speaker has a large effect on stimulus level presented at the eardrum. A person’s head and torso as well as the external ear (e.g., pinna, ear canal, concha) affect sound levels (Shaw, 1974). Differences in SPL at the eardrum are substantial for speaker locations at different distances and different angles relative to the listener. For this reason, sound-field calibration takes into consideration these factors. A mark is usually made on the ceiling (or floor) of the room to indicate the location of the listener during testing. Even at the desired location, stimulus level at the eardrum for some frequencies can vary as much as 20 dB or more by simply having the listener move his or her head (Shaw, 1974). Calibration assumes the listener will always be facing the same direction relative to the sound source (ANSI, 2010). Furniture and other persons in the sound field also affect the stimulus level at a listener’s eardrum (Morgan et al., 1979). All of these factors add to the challenge of obtaining accurate sound-field thresholds.
在声场阈值测试中，听者相对说话者的方位对呈现在鼓膜上的刺激程度有很大影响。一个人的头部和躯干以及外耳（如耳廓、耳道、耳蜗）都会影响声音程度（Shaw, 1974）。相对于听者不同距离和不同角度的扬声器位置，鼓膜声压级的差异是显著的。因此，声场校准要考虑这些因素。通常在房间的天花板（或地板）上做一个标记，以指示测试期间听者的位置。即使在理想的位置，只要听者移动他（她）的头，一些频率在鼓膜上的刺激程度可以变化多达20分贝或更多（Shaw, 1974）。校准假定的是听者始终面对与声源相同的方向（ANSI, 2010）。声场中的设备和其他人也会影响听者鼓膜的刺激程度（Morgan et al.， 1979）。所有这些因素都增加了获得准确声场阈值的难度。
Another important consideration in sound-field threshold measures is the stimulus type. Thresholds corresponding to different frequencies are desired for plotting an audiogram, but puretones can exhibit large differences in level at different positions in a testing suite as a result of standing waves. Standing waves occur when direct sound from the speaker interacts with reflections, resulting in regions of cancellation and summation. Differences in stimulus level due to standing waves are minimized by using narrowband noise or frequency-modulated (FM) tones as the stimulus (Morgan et al., 1979). FM tones, also known as warbled tones, are tones that vary in frequency over a range that is within a few percent of the nominal frequency. This variation occurs several times per second. Under earphones, thresholds obtained with these narrowband stimuli are nearly identical to thresholds obtained with puretones, with some exceptions in persons with steeply sloping hearing loss configurations. FM tones and narrowband noise are the preferred stimuli for sound-field threshold measures.
声场阈值测量中的另一个需要考虑的重要因素是刺激类型。不同频率对应的阈值最终绘制成听力图，但是纯音由于驻波的作用，在测试套件的不同位置可以表现出较大程度的差异。当扬声器直接发出的声音与反射相互作用时，就会产生驻波，从而导致抵消和叠加。通过使用窄带噪声或调频（FM）音调作为刺激最大限度地减少了驻波引起的刺激差异（Morgan等，1979）。FM音调，又称颤音，是指频率变化范围在额定频率的百分之几以内变化的音调。这种变化每秒发生数次。在耳机下，使用这些窄带刺激获得的阈值与使用纯音获得的阈值几乎相同，但对于听力损失严重的人来说有些例外。FM音调和窄带噪声是声场阈值测量的首选刺激。
Bone Vibrators
骨振动器
A bone vibrator is a transducer that is designed to apply force to the skull when placed in contact with the head. Puretone BC thresholds are measured with a bone vibrator like the one illustrated in Figure 3.6. A separation of 15 dB or more between masked AC and BC thresholds, with BC thresholds being lower than AC thresholds, is often evidence of a conductive hearing loss. Other possible explanations for air–bone gaps and bone–air gaps are equipment miscalibration, test–retest variability, and individual differences in anatomy that cause thresholds to deviate from the groupmean data used to derive normative values for relating AC and BC thresholds.
骨振动器是一种换成器，设计用于放置在头部向颅骨施加力。纯音骨导阈值是用骨振动器测量的，如图3.6所示。掩蔽的气骨导阈值之间存在15dB或更高的分离，且骨导阈值低于气导阈值，这通常是传导性听力损失的证据。气-骨间隙和骨-气间隙的其他可能解释是设备校准错误、复测变异性和个体解剖差异，这些因素导致阈值偏离气骨导阈值标准值。
临床骨传导振动器（无线电耳型号B-72）。
For threshold measurements bone vibrators are typically placed behind the pinna on the mastoid process or on the forehead. Although forehead placement produces slightly lower intrasubject and intersubject threshold differences (Dirks, 1994), placement on the mastoid process is preferred by 92% of audiologists (Martin et al., 1998). Mastoid placement is preferred mainly because it produces between 8 and 14dB lower thresholds than forehead placement for the same power applied to the vibrator, depending on the frequency (ANSI, 2010). The median difference is 11.5 dB. Given that the maximum output limits for bone vibrators with mastoid placement are as much as 50 dB lower than that for AC thresholds, forehead placement yields an even larger difference. The inability to measure BC thresholds for higher levels means that a comparison of AC and BC thresholds is ambiguous in some cases. That is, when BC thresholds indicate no response at the limits of the equipment (e.g., 70 dB HL) and AC thresholds are poorer than the levels where no response was obtained (e.g., 100 dB HL), the audiologist cannot establish from these thresholds whether the loss is purely sensory/neural or whether it has a conductive component.
阈值测量时，骨振动器通常放置在耳廓后的乳突上或前额上。虽然前额放置会产生更小的主体内和主体间阈值差异（Dirks，1994），但92％的听力学家首选乳突位置（Martin等人，1998）。首选乳突放置是因为给振动器施加相同的力量，根据频率的不同，其测量出的阈值比前额放置低8到14 dB（ANSI，2010）。中间值为11.5 dB。考虑到乳突放置的骨振动器的最大输出限制比气导阈值低50 dB，前额放置会产生更大的差异。无法测量更高的BC阈值意味着在某些情况下气导和骨导阈值的比较是不明确的。也就是说，当骨导阈值显示在设备极限处无反应（如70dB HL），而气导阈值低于无反应处的骨导阈值（如100dB HL）时，听力学专家不能从这些阈值中确定损失仅仅是感音/神经性损失或是传导性损失。
Test Environment
测试环境
Hearing tests ideally are performed in specially constructed sound-treated chambers with very low background noise. A sound-treated room is not a sound-proof room. High-level external sounds can penetrate the walls of a sound-treated room and may interfere with test results. Because test tones near threshold can be easily masked by extraneous, external noise, test chambers have strict guidelines for maximum permissible ambient noise levels. Low background noise levels are particularly important for BC testing, when the ears remain uncovered. When testing is done in a room that meets the ANSI guidelines, the audiogram reflects that by citing ANSI S3.1 (1999), the standard governing permissible ambient noise levels. Table 3.1 shows the minimum levels of ambient noise measured in octave bands encompassing the test frequency that enable valid hearing threshold measurements at 0 dB HL.
理想的听力测试是在背景噪音非常低的特殊构造的声音处理室中进行的。声音处理室不是隔音室。高强度的外部声音可以穿透声音处理室的墙壁，并可能干扰测试结果。由于接近阈值的测试音调很容易被无关的外部噪声掩盖，因此测试室对最大允许周围环境噪声水平有严格的准则。当耳朵未遮盖时，低背景噪音水平对骨导测试尤其重要。当在符合ANSI准则的房间内进行测试时，听力图反映了标准管理所允许的周围环境噪声程度，准则引用的是ANSI S3.1（1999）。表3.1给出了在0 dB HL下有效听力阈值测量的测试频率范围内，以倍频音程测量的环境噪声的最低水平。
At times, audiologists must estimate hearing thresholds in rooms that do not meet the guidelines for minimal ambient noise. Some patients in hospital rooms or nursing homes must be tested at bedside. In those cases, test results should be clearly marked so that others know the conditions under which the test was done. When possible, these bedside tests should be performed using insert earphones, which provide a greater amount of attenuation in low frequencies where ambient noise is typically more of a problem. In these environments, BC testing, particularly in the low frequencies, may not be valid.
有时，听力师必须在不符合最低环境噪声准则的房间中评估听力阈值。一些住在病房或疗养院的病人必须在床旁接受检查。在这些情况下，应该清楚地标记测试结果，以便其他人知道测试是在什么条件下进行的。如果可能的话，这些床旁测试应该使用插入式耳机，这样在周围环境噪声是比较大的问题时，插入式耳机在低频处可以提供更大的衰减。在这些环境中，骨传导测试，尤其是在低频中，可能是无效的。
改编自美国国家标准学会。（1999年）听力测试室允许的最大周围环境噪声。ANSI S3.1-1999。纽约州纽约市：美国国家标准协会。在测量0 dB HL或更低的有效阈值时倍频音程级别不能超过列表值。
Measuring Puretone Thresholds
测量纯音阈值
Psychophysics is the field of study that relates the physical world with perception. PT thresholds are an example of a psychophysical measure relating the physical characteristics of a tone to a behavioral threshold.
心理物理学是将物理世界与感知联系起来的研究领域。纯音阈值是一种将音调的物理特征与行为阈值联系起来的心理物理测量的例子。
A psychophysical procedure describes the specific method used to obtain behavioral thresholds. The most common one used in puretone audiometry is a modified method of limits. In the method of limits, the tester has control over the stimulus. A threshold search begins with the presentation of a tone at a particular frequency and intensity that is often specified by the procedure. After each presentation of the tone (or a short sequence of pulsed tones), the tester judges whether or not the listener heard it based upon the listener’s response or lack of response. Each response determines the subsequent dB-level presentation. If a tone on a given presentation is not heard, the tone level is raised. If a tone is heard, the level is lowered. The rules of the psychophysical procedure govern the amount of the level change following each response, when to stop the threshold search, and the definition of threshold. The procedure, which is described in detail in subsequent sections, may be modified slightly based on the clinical population (e.g., the age of the listener).
心理物理程序描述了获得行为阈值的具体方法。纯音测听最常用的方法是一种改进的限制法。在限制法中，测试者可以控制刺激。阈值搜索从特定频率和强度的音调开始，该频率和强度通常由程序指定的。在每一次音调的发出之后（或者是一小段脉冲音调序列），测试人员根据听者的反应与否来判断听众是否听到了它。每个反应决定了后续的db程度。如果没有听到给定的演示音调，则提高音调强度。如果听到音调，则降低强度。心理物理程序的规则控制了每个响应之后的程度变化量、何时停止阈值搜索以及阈值的确定。该过程可能会根据临床人群（例如，听者的年龄）稍作修改，将在后续章节中详细描述。
COOPERATIVE LISTENERS AGE 5 YEARS TO ADULT (EARPHONES)
5岁至成人受试者（耳机）
Guidelines for Manual Pure Tone Audiometry is a publication that describes a uniform method for measuring thresholds (American Speech-Language-Hearing Association [ASHA], 2005). The goal of the guideline is to minimize differences across clinics by standardizing procedures. The committee that drafted this consensus document understood that its recommendations represent general guidelines and that clinical populations may require variations of the procedure.
“人工纯音测听指南”是一份介绍测量听阈的统一方法的出版物（美国语言听力协会[ASHA]，2005年）。该指导方针的目标是通过标准化程序最大限度减少不同诊所间的差异。起草这份共识文件的委员会理解，其建议代表一般准则，临床人群可能工作时需要改变程序。
Instructions
说明
Puretone audiometry begins with instructing the individual being tested. The instructions are a critical part of the puretone test, because thresholds measured using this clinical procedure are biased by the willingness of a person to respond. Some listeners wait for a tone to be distinct before they respond, which leads to higher thresholds than for someone who responds whenever they hear any sound that could be the tone. This bias is controlled in the instructions by informing listeners to respond any time they hear the tone no matter how faint it may be. A study by Marshall and Jesteadt (1986) shows that response bias controlled for in this manner plays only a small role (a few dB at most) in PT thresholds obtained using the ASHA guideline. Marshall and Jesteadt (1986) also reported that the response bias of elderly listeners was not different than that of a group of younger persons. Before the study by these authors, it was believed that elderly persons might adopt an extremely conservative response criterion, resulting in artificially elevated thresholds compared to those of younger persons.
纯音测听是从指导被测试者开始。“指导”是纯音测试的一个关键部分，因为使用这一临床程序测量的阈值会因一个人的反应意愿而产生偏差。有些听者会等待清晰的音调才会做出反应，这会导致其反应阈值都要高于那些在听到任何可能是音调的声音都作出反应的人的阈值。这种偏差可以在指导中控制，只要听到音调，无论多么微弱，都要作出反应。Marshall和Jestet（1986）的一项研究表明，以这种方式控制的反应偏差在使用ASHA准则做出的纯音阈值中只起到很小的作用（最多几dB）。Marshall和Jestet（1986）报告还提到，老年人的反应偏差与一组年轻人的反应偏差没什么不同。在这些作者的研究之前，人们认为老年人可能会采用一个非常保守的反应标准，与年轻人相比，这会导致阈值明显升高。
According to the ASHA (2005) guideline, the instructions should also include the response task (e.g., raise your hand or finger, or press a button), the need to respond when the tone begins and to stop responding when it ends, and that the two ears are tested separately. Although not in the ASHA guideline, instructions asking the examinee to indicate which ear the sound is heard in may be useful. This is especially important in cases of unilateral or asymmetrical hearing losses where cross-hearing is possible.
根据ASHA（2005）的指南，指导还应该包括响应任务（例如，举起你的手或手指，或按下一个按钮），当音调开始时作出响应和结束时停止响应，以及两个耳朵分别测试。虽然ASHA指南中没有记录，但是“指导”要求被试者指出在哪个耳朵里听到声音可能是有帮助的。这在可能发生交叉听力的单侧或非对称听力损失的情况下尤为重要。
The examiner should present the instructions prior to placement of earphones. Earphones attenuate external sounds making speech understanding more difficult, particularly for persons with hearing loss. Listeners should also be queried after the instructions are presented to determine if they understood what was said. Sample instructions are given below:
检查者应在放置耳机前说明。带上耳机会使外界声音变弱，使语音理解更加困难，尤其对于有听力损失的人。在给出“指导”之后，还应该询问听者，以确定他们是否理解所讲的内容。示例说明如下：
You are going to hear a series of beeps, first, in one ear and then in the other ear. Respond to the beeps by pressing the button [switch] when one comes on and release it as soon as it goes off. Some of the beeps will be very faint, so listen carefully and respond each time you hear one. Do you have any questions?
你会听到一系列的哔哔声，先是一只耳朵，然后另一只耳朵。当听到哔哔声时，按下【开关】按钮，声音消失时立即松开。有些哔哔声会非常微弱，所以要仔细听，每次听到哔哔声都要做出反应。你有什么问题吗？
Earphone Placement
耳机放置
The earphones should be placed by the examiner. For convenience, earphones are color coded; red and blue correspond to the right and left ears, respectively. Prior to placement of earphones, clients are asked to remove jewelry such as earrings and glasses if they will interfere with the placement of the earphone. This is particularly relevant for supra-aural earphones.
耳机应由检查者放置。为方便起见，耳机采用彩色编码；红色和蓝色依次对应右耳和左耳。在放置耳机之前，如果诸如耳环和眼镜之类首饰干扰耳机的放置，则要求受试者摘除。 这对于压耳式耳机尤为重要。
For circumaural and supra-aural earphones, the diaphragm of the earphone should be centered over the ear canal. The examiner should view each ear while the phone is being placed. Immediately after placement, the headband is tightened enough to make the earphone perpendicular to the floor when the examinee is sitting upright.
对于耳罩式耳机和压耳式耳机，耳机的振膜应位于耳道的中心位置。在放置耳机时，检查者应查看每只耳朵。放置完毕后，立即收紧头带，以便当考生直坐时，耳机垂直于地面。
The first step in placement of insert earphones is to attach a spring-loaded clip that holds the transducer in place to the examinee’s clothing. The clip can be attached to clothing near the shoulder (or behind a child’s neck) to keep the plug from being pulled out of the ear. In some newer implementations that combine middle-ear and otoacoustic emission measurements, the earphone is attached to a headband. For both types of support, the audiologist compresses the foam plug and inserts it into the ear canal so that its outer edge lines up with the tragus.
插入式耳机放置的第一步是将附有弹簧夹的换能器固定在检查者的衣服上。这种夹子可以固定在靠近肩膀（或孩子脖子后面）的衣服上，防止耳塞从耳朵里拉出来。在一些结合中耳测量和耳声发射测量的较新型装置中，耳机附在头带上。对于这两种类型的设备，听力师压缩泡沫塞并将其插入耳道，使其外缘与耳屏对齐。
Placement of the Bone-conduction Vibrator
骨传导振动器的放置
Although some recommend forehead placement (Dirks, 1994), typically audiologists place the BC oscillator on the most prominent part of the mastoid process. While holding the oscillator against the mastoid process with one hand, the headband is fit over the head to hold the oscillator in place using the other hand. The oscillator surface should be set directly against the skin, not touching the pinna, and with no hair or as little hair as possible between the oscillator and the skin. Some audiologists play a continuous lowfrequency tone while moving the oscillator slightly side to side, asking the listener to report the location at which the tone is the strongest.
尽管有人建议前额放置（Dirks，1994），但通常听力师将骨传导振动器置于乳突最突出的部位。用一只手将振荡器固定在乳突上，头带戴在头上，另一只手将振动器固定在适当的位置。振动器表面应直接贴在皮肤上，不要接触耳廓，并且在振荡器和皮肤之间不要有毛发或尽可能少的毛发。一些听力专家在轻轻左右移动振荡器的同时播放连续的低频音调，要求听者报告音调最强的位置。
Audiometric Procedure for Threshold Measurement
听阈测量程序
The ASHA Guideline (2005) recommends starting a threshold search from either well below threshold or using a suprathreshold tone that familiarizes the participant with the stimulus. Most clinicians prefer the familiarization method. For the familiarization approach, testing usually begins at 1,000 Hz at 30 dB HL unless prior knowledge of the examinee’s hearing suggests otherwise (ASHA, 2005). At 1,000 Hz, an examinee is more likely to have residual hearing than at a higher frequency, and test–retest reliability is excellent. Testing begins with an examinee’s self-reported better ear. If the examinee believes both ears are identical, testing begins by convention with the right ear. The better ear is tested first to provide a reference to know whether masking needs to be delivered to obtain a valid estimate of threshold for the poorer ear.
ASHA指南（2005）建议从低的阈值或使用听者熟悉刺激的阈上音调开始阈值搜索。大多数临床医生更喜欢“熟悉性”的方法。对于“熟悉性”方法，除非事先了解受试者的听力，否则测试通常从1000 Hz，30 dB HL开始（ASHA，2005）。受试者在1,000 Hz比更高频率更容易出现残余听力，并且复测可靠性好。测试从受试者自我感觉听力更好的耳朵开始。如果受检者认为双耳听力是相同的，则按照惯例从右耳开始测试。首先对较好的耳朵进行测试，以提供一个参考，了解是否需要提供掩蔽以获得对差耳阈值的有效评估。
Tonal duration is an important factor in a puretone test. On most audiometers, the option exists to select either pulsed or manual presentation. A 1- to 2-second duration tone is recommended for manual presentation (ASHA, 2005). The duration is determined by the amount of time the interrupter switch is held down. Pulsed tones are achieved by selecting this option on the audiometer’s front panel. If pulsed tones are selected, then the audiometer alternately presents the tone followed by a short silent interval (typically 225 ms on followed by 225 ms off) for as long as the interrupter switch is depressed. The minimum duration for a single pulse of the tone is critical. Numerous psychoacoustic studies have shown that tonal durations between roughly 200 ms and 1 second or more yield nearly identical thresholds (Watson and Gengel, 1969). By contrast, the same studies show that durations less than 200 ms result in higher thresholds. For this reason, audiometers are designed to have a nominal pulse duration of 225 ms (ANSI, 2010). Pulsed and manually presented tones presented from audiometers that maintain tonal durations between 200 ms and 2 seconds yield nearly identical thresholds, as the psychoacoustic studies suggest. However, pulsed tones are preferred for two reasons. Most patients prefer pulsed tones (Burk and Wiley, 2004), and pulsed tones also reduce the number of presentations required to find threshold in persons with cochlear hearing loss who have tinnitus (Mineau and Schlauch, 1997). Apparently, pulsed tones help patients to distinguish the puretone signal from the continuous or slowly fluctuating noises generated from within their auditory system (tinnitus), thereby reducing false-positive responses. False-positive responses can lengthen test time (Mineau and Schlauch, 1997), which is costly to an audiology practice.
音调持续时间是纯音测试中的一个重要因素。在大多数听力计上，可以选择脉冲或手动演示。1到2秒的持续音调被建议于手动演示时使用（ASHA，2005）。持续时间由中断开关按下的时间长短确定。脉冲音调是通过在听力计的前面板上选择此选项来实现的。如果选择脉冲音调，则只要按下中断开关，听力计就会交替呈现音调和一个短的无声间隔。（通常为225毫秒打开，然后225毫秒关闭）。音调的单一脉冲的最短持续时间至关重要。大量的心理声学研究表明，大约200毫秒到1秒或更长时间的音调持续时间产生几乎相同的阈值(Watson和Gengel，1969)。相反，同样的研究表明，小于200ms的持续时间会导致更高的阈值。因此，听力计的额定脉冲持续时间为225毫秒（ANSI，2010年）。心理声学研究表明，由听力计呈现的脉冲和手动呈现的音调在200毫秒到2秒之间产生几乎相同的阈值。然而，首选脉冲音有两个原因。大多数患者更喜欢脉冲音调（Burk和Wiley，2004年），脉冲音调也减少了患有耳鸣的耳蜗性听力损失患者找到阈值所需的呈现次数（Mineau和Schlauch，1997年）。显然，脉冲音调可以帮助患者区分纯音信号和听觉系统（耳鸣）中产生的持续或缓慢的噪声，从而减少假阳性反应。假阳性反应会延长测试时间(Mineau和Schlauch，1997)，这对听力学实践来说代价很高。
Thresholds typically are obtained using a modified Hughson–Westlake down-up procedure, which is a specific implementation of a method-of-limits procedure (Carhart and Jerger, 1959; Hughson and Westlake, 1944). The examiner begins the threshold-finding procedure by presenting a tone at 30 dB HL (ASHA, 2005). If the listener responds, the level of the tone is decreased in 10-dB steps until the listener no longer responds. If the listener does not respond to this initial 30-dB tone, the examiner raises the tone in 20-dB steps until a response is obtained. After every response to a tone, the level of the tone is decreased in 10-dB steps until there is no response. For subsequent presentations when there is no response, the examiner raises the level of the tone in 5-dB steps until a response is obtained. Following this “down-10/up-5” rule, the tester continues until the threshold is bracketed a few times, and a threshold estimate is obtained. ASHA (2005) recommends that threshold should correspond to the level at which responses were obtained for two ascending runs, which is what most clinicians based their thresholds on even when the ASHA (1978) Guideline recommended that thresholds be based on three ascending runs. Research based on computer simulations of clinical procedures (Marshall and Hanna, 1989) supports the clinician’s position and that of the ASHA (2005) guideline. The computer simulations of thresholds based on three ascending runs showed only a minimal reduction of the variability when compared to thresholds based on two ascending runs. Listeners who produce inconsistent responses are an exception, and for these listeners, additional measurements can be made to confirm the threshold estimate.
阈值通常是使用修改后的HW升降法获得的，该过程是限制法的具体实现（Carhart and Jerger，1959；Hughson and Westlake，1944）。测试者通过30dBHL的音调开始阈值测试过程（Asha，2005年）。如果受试者响应，则音调以每次10dB降低，直到受试者不再响应。如果听者对最初的30分贝音调没有反应，则检查者以每次20dB提升音调，直到出现响应。在对音调的每次响应之后，音调以每次10dB降低，直到没有响应。对于没有响应的情况下，检查者以每次5dB提升音调，直到获得响应。在该“降10 /升5”规则之后，测试继续，直到阈值被大致测到几次，并获得阈值评估值。ASHA（2005）建议阈值应该对应于两次上升时的响应的水平，这是大多数临床医生基于的阈值，即使ASHA（1978）指南建议阈值基于三次上升时的响应的水平。基于计算机模拟临床程序的研究（Marshall和Hanna，1989）支持临床医生的立场和ASHA（2005）指南的立场。基于三次上升运行的阈值的计算机模拟显示，与基于两次上升运行的阈值相比，只有很小的降低。产生不一致响应的受试者是一个例外，对于这些受试者，可以进行额外的测量以确定阈值评估值。
After a threshold is measured at 1,000 Hz, the next frequencies that are examined depend on the goal, but the higher frequencies are typically tested prior to the lower frequencies. For diagnostic audiometry, thresholds are measured at octave intervals between 250 and 8,000 Hz, along with 3,000 and 6,000 Hz. Intra-octave thresholds between 500 and 2,000 Hz should be measured when thresholds differ by 20 dB or more between two adjacent octaves. ASHA (2005) also recommends that 1,000 Hz be tested twice as a reliability check. Refer to the ASHA (2005) guidelines for specifics about the recommended protocol and Chapter 6 for details about the use of masking noise to eliminate the participation of the nontest ear. Masking noise is needed whenever the threshold difference between ears is equal to or exceeds the lowest possible values for interaural attenuation. For BC testing, masking is needed to verify results anytime an air–bone gap in the test ear of greater than 10 dB is observed. For AC testing, masking is needed when the difference between the AC threshold in the test ear and the BC threshold of the nontest ear is greater than or equal to 40 dB for supra-aural earphones, and considerably more for insert earphones, especially in the low frequencies (Killion and Villchur, 1989). Specific recommendations for insert earphones cannot be made until a study with a larger sample size is completed.
在以1,000Hz测量阈值之后，下一个被检查的频率取决于所需目标，但是通常较高频率在较低频率之前测试。对于诊断听力测量，阈值测量的倍频音程在250至8，000赫兹之间，以及3，000和6，000赫兹。当两个相邻倍频音程之间的阈值相差20 dB或更多时，应测量500到2,000 Hz之间的半倍频程阈值。ASHA（2005）还建议将1000hz测试两次作为可靠性检查。有关使用掩蔽噪声消除非测试耳朵参与的详细信息，请参阅ASHA（2005）指南中的具体推荐方案和第6章的内容。只要两耳之间的阈值差等于或超过耳间衰减的最低可能值时，就需要施加掩蔽噪声。对于骨导测试，只要观察到测试耳中的气骨间隙大于10 dB，就需要进行掩蔽以验证结果。在气导测试中，使用压耳式耳机时，当测试耳的气导阈值与非测试耳的骨导阈值之间的差异大于或等于40dB时，需要掩蔽，对于插入式耳机，尤其是在低频时，掩蔽值要大的多（Killion和Villchur，1989）。在完成较大样本量研究之前，不能对插入式耳机做出具体建议。
TESTING CHILDREN YOUNGER THAN AGE 5 YEARS AND PERSONS WITH SPECIAL NEEDS
测试对5岁以下儿童及有特殊需要的人员
For most children younger than age 5 years, audiologists have special procedures that they employ to measure PT thresholds. Some of these same procedures are also appropriate for persons older than 5 years who have cognitive deficits. Chapter 24 on pediatric hearing assessment describes these procedures and their interpretation.
对于大多数5岁以下的儿童，听力学家采用特殊方法来测量纯音阈值。其中一些同样的方法也适用于5岁以上有认知缺陷的人。第24章描述了关于儿科听力评估程序及其解读。
Audiometric Interpretation
听力测定解读
PT thresholds are displayed in tabular or graphical formats. The tabular format is useful for recording the results of serial monitoring of thresholds, as in a hearing conservation program, but in many applications, thresholds are plotted on an audiogram. ASHA (1990), in a publication entitled Guidelines for Audiometric Symbols, suggests a standardized form for the audiogram. Although other formats for plotting audiograms are acceptable, it is helpful to use a standardized format for ease of interpretation across clinics. The audiogram consistent with that recommended in the ASHA guidelines (1990) is shown in Figure 3.7 along with recommended symbols. This audiogram only covers the conventional frequencies. Thresholds for extended high frequencies are plotted often in units of dB SPL, because average extended high-frequency thresholds vary over a wide range with the age of the listener, making dB SPL a better reference than dB HL for comparing thresholds to norms for listeners of different ages. Conversion between units of dB SPL and dB HL can be accomplished for three different earphone models by consulting reference levels published in ANSI (2010).
纯音阈值以表格或图形格式显示。表格格式对于记录连续监测阈值的结果很有用，就像在听力保护程序中一样，但在许多应用中，阈值被绘制在听力图上。ASHA（1990）在题为“听力符号指南”的出版物中提出了听力图的标准化格式。尽管使用其他格式绘制听力图也是可以接受的，但使用标准化格式以助于临床之间的解释。如图3.7展示了符合ASHA指南（1990）建议的听力图，并附有推荐符号。该听力图只包含常规频率。扩展高频的阈值通常以dB SPL为单位绘制，因为扩展高频的平均阈值随着受试者的年龄在变化范围很大，使得dB SPL比dB HL更适合于比较不同年龄的听者的常规阈值。通过参考ANSI（2010）中公布的参考数据，可以针对三种不同的耳机型号实现dB SPL和dB HL之间的转换。
Audiograms are often classified by categories based on the degree of hearing loss. A number of authors have published systems for classifying hearing loss based on the average AC thresholds for three frequencies. The frequencies used for this purpose are usually 500, 1,000, and 2,000 Hz, often referred to as the three-frequency puretone average (PTA). Table 3.2 shows the categories for the degree of loss based on this PTA for three different authors (Goodman, 1965; Jerger and Jerger, 1980; Northern and Downs, 2002). The first category is normal hearing. Note that none of the three authors agree on the upper limit for normal, which ranges from 15 to 25 dB HL. Northern and Downs (2002) suggest using 15 dB HL as the upper limit for normal hearing for the three-frequency PTA for children between 2 and 18 years of age and a higher limit for adults. A 15 dB HL upper limit for normal hearing may produce a significant number of false positives when applied to thresholds for individual audiometric frequencies, even in children (Schlauch and Carney, 2012). Regardless of the value used as an upper limit for normal hearing, keep in mind that an ear-related medical problem can still exist even though all thresholds fall within the defined normal range. For example, the presence of a significant air–bone gap might indicate the presence of middle-ear pathology even though all AC thresholds fall within normal limits.
听力图通常根据听力损失程度按类别分类。许多作者已经公布了基于三个频率的平均气导阈值对听力损失进行分类的系统。用到的频率通常为500,1,000和2,000Hz，通常称为三频纯音平均值（PTA）。表3.2给出了三个不同作者基于PTA的损失程度分类（Goodman，1965; Jerger和Jerger，1980; Northern和Downs，2002）。第一类是正常听力。请注意，三位作者均未就正常上限达成一致，范围为15至25 dB HL。 Northern和Downs（2002）建议使用15 dB HL作为2至18岁儿童的三频纯音平均值（PTA）的正常听力上限，成人使用较高上限。当应用于个别测听频率的阈值时，正常听力的上限15dbHL可能会产生大量的假阳性，即使在儿童中也是如此（Schlauch和Carney，2012）。不管用什么值作为正常听力的上限，请记住，即使所有阈值都在规定的正常范围内，与耳朵有关的医学问题仍然可能存在。例如，即使所有气导阈值都在正常范围内，但显著的气骨间隙可能表明存在中耳病变。
The original intent of classification system for severity of loss based on a three-frequency PTA was to express, in a general way, the degree of handicap associated with the magnitude of the loss. These categories are only somewhat successful at achieving this goal, because (1) handicap is dependent on many factors related to an individual’s needs and abilities, (2) only some of the speech frequencies are assessed using this three-frequency average (speech frequencies range from 125 to 6,000 Hz), and (3) identical amounts of hearing loss sometimes result in large differences in the ability to understand speech and, as a consequence, the degree of disability associated with the loss. Despite these limitations, many audiologists use these categories routinely to summarize the amount of loss in different frequency regions of an audiogram when describing results to other professionals or to a client during counseling.
基于三频PTA的损失严重程度分级系统的最初目的是以一般方式表示与损失程度相关的障碍程度。这些类别只在一定程度上成功地实现了这一目标，因为（1）障碍取决于与个人需求和能力相关的许多因素，（2）只有部分语音频率是用这三个频率的平均值进行评估（语音频率在125至6，000 Hz之间），（3）相同数量的听力损失有时会导致理解语言能力的巨大差异，从而导致与听力损失相关的残疾程度。尽管有这些限制，但许多听力学家在向其他专业人员或咨询期间的客户描述结果时，经常使用这些类别来总结听力图不同频率区域的损失量。
Another factor in audiometric classification is the type of hearing loss. The type of hearing loss is determined by comparing the amount of hearing loss for AC and BC thresholds at the same frequency. A sensory/neural hearing loss has an equal amount of loss for AC and BC thresholds (as shown in Figure 3.7). By contrast, a conductive loss has lower BC thresholds than AC thresholds (as shown in Figure 3.8). Conductive-loss magnitude is described by the decibel difference between AC and BC thresholds. This difference is known as the air–bone gap, a value that has a maximum of about 65 dB† (Rosowski and Relkin, 2001). Due to test–retest differences, an air–bone gap needs to exceed 10 dB before it is considered significant. A mixed hearing loss shows a conductive component and a sensory/neural component. In other words, a mixed loss has an air–bone Classification gap, and the thresholds for BC fall outside the range of normal hearing (Figure 3.9).
听力损失分级的另一个因素是听力损失的类型。通过比较相同频率下气导和骨导阈值的听力损失量来确定听力损失的类型。感音/神经性听力损失中气导和骨导阈值具有相等的损失量（如图3.7所示）。相比之下，传导性听力损失中骨导阈值损失低于气导阈值（如图3.8所示）。传导损耗幅度是通过气导和骨导阈值之间的分贝差来描述。这种差异被称为气骨间隙，最大值约为65 dB（Rosowski和Relkin，2001）。由于复测的差异，气骨间隙需要超过10 dB才被认为是显著的。混合性听力损失包含传导性成分和感觉/神经性成分。换句话说，混合损失具有气骨间隙，并且骨导的阈值在正常听力范围之外（图3.9）。
Yet another way that audiograms are described is by the hearing-loss configuration. The configuration takes into account the shape of the hearing loss. A description of the configuration of the loss helps in summarizing the loss to patients and to other professionals and often provides insight into the etiology or cause of the loss. Some typical shapes and the criteria used to describe them are shown in Table 3.3.
描述听力图的另一种方式是听力损失结构。该结构考虑了听力损失的形状。对损失结构的描述有助于对患者和其他专业人员的不足进行总结，并常常有助于了解损失的病因或原因。表3.3显示了一些典型的形状和用于描述它们的标准。
An audiogram is summarized verbally by the degree, type, and configuration of the hearing loss for both ears. If a person has normal thresholds in one ear and a hearing loss in the other ear, this is known as a unilateral hearing loss. A loss in both ears is described as a bilateral hearing loss. Bilateral losses are described as symmetric (nearly equal thresholds in both ears) or asymmetric.
听力图是根据双耳听力损失的程度、类型和结构口头总结出来的。如果一个人的一只耳朵有正常的阈值，另一只耳朵有听力损失，这就是所谓的单侧听力损失。双耳的损失称为双侧听力损失。双侧损失分为对称（双耳阈值几乎相等）或不对称。
Some Limitations of Puretone Testing
纯音测试的一些局限性
TEST–RETEST RELIABILITY
复测可靠性
PT thresholds are not entirely precise. Consider a cooperative adult whose AC thresholds are measured twice at octave intervals between 250 and 8,000 Hz. For these two measures, assume too that the earphones are removed and replaced between tests. For this situation, the probability of obtaining identical thresholds at each frequency is small. This is due to test–retest variability. Test–retest variability is also responsible for BC thresholds not always lining up with AC thresholds in persons with pure sensory/neural losses. As reported by Studebaker (1967), test–retest variability causes false air–bone gaps and false bone–air gaps (BC thresholds poorer than AC thresholds). The source of this variability is a combination of variations in the person’s decision process, physiologic or bodily noise, a shift in the response criterion, and differences in transducer placement. It is assumed that the equipment is calibrated correctly for successive tests and that the standard is not in error (Margolis et al., 2013).
纯音阈值并不完全准确。考虑一个成人合作者，其气导阈值在250到8,000 Hz之间的倍频音程将测量两次。对于这两次措施，假设耳机在测试之间被移除和更换。对于这种情况，在每个频率上获得相同阈值的概率很小。这是由于复测的变异性。复测变异性也是导致单纯感音/神经性损伤患者的骨导阈值与气导阈值不总是一致的原因。正如Studebaker（1967）报道的那样，复测的变异性导致假的气骨间隙和假的骨气间隙（骨导阈值比气导阈值差）。这种变异性的来源是人的决策过程中的变化、生理或身体噪声、反应标准的变化和换能器位置的差异的组合。假设设备已针对连续试验进行了正确校准，并且标准无误(Margolis et al., 2013)。
The inherent variability of PT thresholds poses a problem for audiologists who are faced with making clinical decisions based on these responses. Audiologists frequently need to assess whether hearing has changed significantly since the last test, whether hearing is significantly better in one ear than the other, and whether an air–bone gap is significant.
纯音阈值的固有变异性给听力学家提出了一个问题，他们要根据这些反应做出临床决策。听力学家经常需要评估自上次测试以来，听力是否发生了显著的变化，一只耳朵的听力是否明显好于另一只耳朵，以及气骨间隙是否显著。
A good place to begin with understanding test–retest variability is to consider the standard deviation (SD) of test–retest differences at a single frequency. When a 5-dB SD is assumed, threshold differences on retest of 15 dB or more are rarely expected if only a single threshold measurement is retested. By contrast, when complete audiograms are assessed, the likelihood of obtaining a large threshold difference at one frequency on retest increases. For example, 15 dB or greater differences on retest are expected only 1.24% of the time when the threshold for a single frequency is assessed. When thresholds for six frequencies are assessed in each ear (octave intervals between 0.25 and 8 kHz), 14% of the persons tested would be expected to have at least one threshold differing by 15 dB or more (Schlauch and Carney, 2007). Thus, differences of 15 dB or more in these applications would be much more commonplace than those predicted by the SD of inter-test differences for a single frequency.
理解复测变异性的一个好的起点是考虑在单个频率下测试重测差异的标准偏差（SD）。当假设5dB SD时，如果只对单个阈值测量进行了重新测试，则重新测试时的阈值差异很少达到15 db或更大。相比之下，当对整个听力图进行评估时，重新测试时在一个频率上获得较大阈值差的可能性增加。例如，当评估单个频率的阈值时，预计出现5dB或更大重测差异仅为1.24%。当在每个耳朵中评估6个频率的阈值（0.25到8千赫之间的倍频音程）时，14%的被测试者预计至少有一个阈值相差15分贝或更多（Schlauch和Carney，2007年）。因此，在这些情景中15dB或更大的差异将比单个频率测试间的标准差预测的差异更为常见。
Several methods have been proposed to assess the significance of threshold differences on retest for complete audiograms (Schlauch and Carney, 2007). These methods usually require that thresholds for more than one frequency contribute to the decision process, although some accept a large change for a single frequency, such as 20 dB or more, as a significant difference. One of these methods defines a significant threshold shift by a minimal change in a PTA. For instance, the Occupational Safety and Health Administration (1983) defines a notable threshold shift (in their terminology, a standard threshold shift) as a 10-dB or greater change in the PTA based on thresholds for 2, 3, and 4 kHz in either ear. These frequencies were selected because they include those that are susceptible to damage by occupational noise and have stable test–retest reliability. A second commonly used approach requires threshold differences to occur at adjacent frequencies. One rule that is applicable to many situations defines a significant threshold shift as one for which two adjacent thresholds differ by 10 dB or more on retest. This criterion has been applied widely in audiometric studies and is sometimes combined with other criteria to arrive at a decision (ASHA, 1994). A third approach recommends repeating threshold measurements during a single session to improve audiometric reliability (National Institute for Occupational Safety and Health, 1998). This method is paired with a rule or rules defining the criterion for a significant threshold shift. The notable difference between this method and the others described earlier is that the criterion defining a threshold shift must be repeatable to be accepted as significant.
有几种方法被提出用来评估整个听力图重测中阈值差异的显著性（Schlauch和Carney，2007）。这些方法通常要求多个频率的阈值参与决策过程，尽管有些方法接受单个频率（如20 dB或更多）的较大变化作为显著差异。其中一种方法通过PTA中的最小变化来确定显著的阈值偏移。例如，职业安全和健康管理局（1983年）根据任一耳中2、3和4 kHz的阈值改变10 dB或更大的PTA变化，确定了一个显著的阈值偏移（在其术语中，标准阈值偏移）。选择这些频率是因为它们包括那些易受职业噪声损害并具有稳定的复测信度的频率。第二种常用的方法要求在相邻频率处出现阈值差异。一个适用于许多情况的规则是将标记阈值偏移定义为两个相邻阈值在重测时相差10dB或更多。这一标准在听力学研究中得到了广泛的应用，有时还与其他标准相结合以做出决定（ASHA，1994）。第三种方法建议在单个会话期间重复阈值测量以提高听力测量的可靠性（National Institute for Occupational Safety and Health，1998）。该方法与一个或多个规则结合，这些规则定义了显著阈值偏移的标准。此方法与前面描述的其他方法之间的显着差异在于，定义阈值偏移的标准必须是可重复的，才能被认为显著的。
The examples in this section on the variability of PT thresholds have assumed a fixed SD of test–retest differences of ±5 dB for all audiometric frequencies. Although 5 dB is a reasonable average value for many situations, studies show that the SD varies with type of earphone, the time between tests, and even with audiometric frequency (Schlauch and Carney, 2007)
本节中有关纯音阈值变异性的示例假设了一个固定的标准差，即所有测听频率的重测差异为±5dB。虽然在许多情况下，5dB是一个合理的平均值，但研究表明，标准偏差（sd）会随耳机类型、测试间隔时间、甚至听力测量频率而变化。
VIBROTACTILE THRESHOLDS
振动触觉阈值
In persons with significant hearing losses, sound vibrations produced by earphones and bone vibrators may be perceived through the sense of touch. Such thresholds are known as vibrotactile thresholds.
对于严重听力受损的人来说，耳机和骨振动器产生的声音振动可通过触觉感知。这种阈值称为振动触觉阈值。
Figure 3.10 illustrates the range of levels found to yield vibrotactile thresholds for a supra-aural earphone and a bone vibrator. A threshold occurring within the range of possible vibrotactile thresholds is ambiguous; it could be a hearing threshold or a vibrotactile threshold. Because relatively low vibrotactile thresholds are observed for BC at 250 and 500 Hz, a false air–bone gap is likely to occur in persons with significant sensory/neural losses at these frequencies.
图3.10说明了为压耳式耳机和骨振动器产生振动触觉阈值的水平范围。在可能的振动阈值范围内出现的阈值是不明确的；可以是听力阈值或振动触觉阈值。由于在250和500 Hz下观察到的骨导振动触觉阈值相对较低，因此在这些频率下，感音/神经性损失较大的人很可能出现假的气-骨间隙。
Boothroyd and Cawkwell (1970) recommend asking the client if they “feel” the stimulus or “hear” the stimulus as a means to differentiate between these two outcomes. Persons with experience with auditory sensations can usually make this distinction.
Boothroyd和Cawkwell（1970）建议询问患者是“感觉到”刺激还是“听到”刺激，以此作为区分这两种结果的一种方法。有听觉感受经验的人通常可以做出这种区分。
The values for vibrotactile thresholds illustrated in Figure 3.10 are based on only nine listeners. A more detailed study needs to be conducted to specify these ranges more precisely for the transducers in current use.
图3.10所示的振动触觉阈值仅基于9个受试者。需要进行更详细的研究，以便更准确地为当前使用的换能器指定这些范围。
BONE-CONDUCTION THRESHOLDS: NOT A PURE ESTIMATE OF SENSORY/NEURAL RESERVE
骨传导阈值：感觉/神经的性损伤的非纯粹评估
The goal of BC testing is to obtain an estimate of sensory/ neural reserve, but BC thresholds sometimes are influenced by the physiologic properties of the external, middle, and inner ears. The BC vibrator sets the skull into vibration, which stimulates the cochlea, but this does not happen in isolation. When the skull is vibrated, the middle-ear ossicles are also set into motion, and this inertial response of the ossicular chain contributes to BC thresholds. Changes in the external and middle ear can modify the contribution of the inertial response, which may result in significant changes in BC thresholds (Dirks, 1994).
骨导测试的目的是获得感音/神经性听力损失的估值，但是骨导阈值有时会受到外、中、内耳生理特性的影响。骨导振动器使颅骨振动，从而刺激耳蜗，但这不是孤立发生的。当颅骨振动时，中耳听小骨也开始运动，听骨链的惯性响应有助于骨导阈值。外耳和中耳的变化可以改变惯性响应，这可能导致骨导阈值的显著变化（Dirks, 1994）。
A classic example of a middle-ear problem that influences BC thresholds is otosclerosis. Otosclerosis frequently causes the footplate of the stapes to become ankylosed or fixed in the oval window. This disease process and some other types of conductive losses (e.g., glue ear) (Kumar et al., 2003) reduce the normal inertial response of the ossicles to BC hearing. The result is poorer thresholds that form a depressed region of BC hearing known as Carhart’s notch (Carhart, 1950). This notch, which typically shows poorer BC thresholds between 500 and 4,000 Hz with a maximum usually at 2,000 Hz of 15 dB, disappears following successful middle-ear surgery. The finding that BC thresholds improve following middle-ear surgery is strong evidence that these poorer BC thresholds observed in stapes immobilization are due to a middle-ear phenomenon rather than a change in the integrity of the cochlea.
中耳问题影响骨导阈值的一个典型例子是耳硬化症。耳硬化症通常导致镫骨的足板变得僵硬或固定在卵形窗。该疾病和一些其他类型的传导性损失（例如，胶耳）（Kumar等人，2003）降低了听小骨对骨导听力的正常惯性响应。结果是较差的阈值形成了一个骨导听力的下降区域，被称为“卡哈切记”（Carhart，1950）。此切迹通常在500-4000 Hz之间出现较差的骨导阈值，最大值通常在2000 Hz，15dB，在成功施行中耳手术后消失。中耳手术后发现骨导阈值改善表明，在镫骨固定中观察到的这些较差的骨导阈值是由于中耳现象而不是耳蜗完整性的改变。
A frequently observed example of middle-ear problems affecting BC thresholds occurs in persons with otitis media with effusion. In this group, falsely enhanced BC thresholds in the low frequencies (1,000 Hz and below) are seen often. The magnitude of the enhancement can be as much as 25 dB (Snyder, 1989). Upon resolution of the middle-ear problem, these previously enhanced BC thresholds become poorer and return to their premorbid values.
中耳问题影响骨导阈值的一个常见例子发生在分泌性中耳炎患者身上。这一组中，在低频（1，000 Hz及以下）中经常看到虚假增强的骨导阈值。增强的幅度可达25dB（Snyder，1989）。在中耳问题解决后，这些先前增强的骨导阈值变得更差，并恢复到其发病前的值。
Similarly, enhancement in BC thresholds occurs for low frequencies with occlusion of the external ear canal by a supra-aural ear phone. This low-frequency BC enhancement, known as the occlusion effect, must be considered when occluding the nontest ear to present masking noise during BC testing. However, when the masking noise is presented using an insert earphone with the foam plug inserted deeply into the ear canal, the amount of the lowfrequency enhancement is smaller than it is when supraaural earphones are used to deliver the masking noise (Dean and Martin, 2000). Further, apparent enhancement of BC thresholds can occur in cases of superior canal dehiscence (see Chapter 4).
类似地，当外耳道被压耳式耳机堵塞时，低频率的骨导阈值也会增强。这种低频骨导增强，即堵耳效应，在遮挡非测试耳时必须加以考虑，以决定是否在骨导测试期间施加掩蔽噪声。但是，当在施加掩蔽噪声时，使用将泡沫塞深插入耳道的插入耳机，其低频增强量比使用压耳式耳机的要小（Dean和Martin，2000）。此外，在上半规管裂的病例下，骨导阈值也会出现明显的增强。（见第四章）
Special Populations
特殊人群
TINNITUS
耳鸣
Many people who come for hearing testing experience tinnitus, the sensation of hearing internal sounds when no sound is present (see Chapter 35). Tinnitus can interfere with the perception of test tones, which can lead to a large number of false-positive responses, and false-positive responses can produce an inaccurate (too sensitive) threshold estimation. Some listeners simply require additional instruction and encouragement to wait until they are more certain they have heard a test tone. In some cases, the audiologist can present a clearly audible tone at the test frequency to remind the listener of the test tone. For more intractable cases, the examiner can present a series of pulsed tones and ask the listener to count the number of tones. It is important with listeners who are giving false-positive responses to avoid a fixed presentation rhythm and to provide irregular intervals of “no trial” silence to confirm that their responses are, in fact, responses to test tones.
许多来进行听力测试的人都会有耳鸣的经历，即在没有声音时听到内部声音的感觉（见第35章）。耳鸣会干扰对测试音调的感知，这可以导致大量的假阳性反应，而假阳性反应可以产生不准确（过于敏感）的阈值评估。一些听众只需要额外的指导和鼓励，直到他们更确定听到测试音。在某些情况下，听力师可以在测试频率上给出清晰可听的音调，以提醒听者注意测试音调。对于更难处理的情况，检查者可以呈现一系列脉冲音，并要求听者计算音调的数量。对于那些给出假阳性反应的听众来说，重要的是要避免测试音调呈现固定的节奏，并提供不规则的“无测试”沉默间隔，以确认他们的反应实际上是对测试音调的反应。
In rare cases, patients have tinnitus resulting from blood flowing nearby auditory structures. Blood flowing through a vein or artery sometimes produces masking noise or “bruit” that can elevate thresholds for low-frequency tones (Champlin et al., 1990). On the audiogram, this form of tinnitus may produce an apparent sensory/neural loss. The loss occurs because the tinnitus masks AC and BC thresholds. Bruit, a recordable form of tinnitus resulting from vibrations in the head or neck, is documented by audiologists by measuring sound levels in the ear canal (Champlin et al., 1990). This problem is treatable when the problem is caused by a vein. In a case study reported by Champlin et al. (1990), the patient received some reduction in tinnitus loudness before surgery by applying pressure to her neck. Surgical ligation of the vein responsible for the tinnitus was shown to be an effective treatment. Surgery reduced tinnitus loudness, SPLs of the bruit measured in the ear canal were lower, and the audiogram showed significantly improved thresholds.
在极少数情况下，病人耳鸣是由于听觉结构附近的血流引起的。流经静脉或动脉的血液有时产生掩蔽噪声或“杂音”，这种情况会提高低频音的阈值（Champlin等人，1990）。在听力图中，这种形式的耳鸣可能产生明显的感音/神经性损失。因为耳鸣会掩盖气导和骨导阈值，所以会发生损失。杂音是一种可记录的由头或颈部振动引起的耳鸣，听力学家通过测量耳道内的声级记录了这种情况（Champlin等人，1990）。当这个问题由静脉引起时是可以治疗的。在Champlin等人（1990年）报告的一个病例研究中，病人在手术前通过对颈部施加压力来减轻耳鸣的响度。手术结扎引起耳鸣的静脉被证明是一种有效的治疗方法。手术可降低耳鸣响度，耳道杂音声压级变低，听力图上的阈值明显改善。
PSEUDOHYPACUSIS
伪聋
Pseudohypacusis, also known as functional hearing loss and nonorganic hearing loss, is the name applied to intra-test and inter-test inconsistencies that cannot be explained by medical examinations or a known physiologic condition (Ventry and Chaiklin, 1965). Most persons who present with this condition are feigning a hearing loss for monetary or psychological gain, but a very small percentage of persons have subconscious motivations related to psychological problems (see Chapter 33).
伪聋，也被称为功能性听力损失和非器质性听力损失，是不能用医学检查或已知的生理状况来解释的测试内和测试间不一致的名称（Venter和Chaiklin，1965）。大多数患有这种情况的人为了金钱或心理上的利益而假装听力丧失，但极少数人有与心理问题有关的潜意识因素（见第33章）。
Persons presenting with pseudohypacusis are often identified from inconsistencies in their responses to the puretones. In addition to general poor reliability during threshold searches, there is a tendency for the threshold to become poorer as more presentations are made (Green, 1978). Methods of identifying the pseudohypacusis by comparing PT thresholds with other measures and the use of special tests are covered in Chapter 33.
表现伪聋的人通常从他们对纯音不一致的反应中辨别出来。除了在阈值搜索期间的一般较差的可靠性之外，随着更多的呈现，阈值有变差的趋势（Green，1978）。通过比较纯音阈值与其他测量值以及使用特殊测试来识别伪聋的方法将在第33章介绍。
AUDITORY NEUROPATHY
听神经病
Auditory neuropathy (or auditory dys-synchrony) is a condition that may account for 11% of hearing losses found in children at risk for hearing loss (Rance et al., 1999). Information about this disorder may be found in Chapters 13 and 19. Many of these children appear to be severely hard of hearing because of very poor speech recognition; however, PT thresholds do not follow any specific pattern. Puretone hearing thresholds for these children range from minimal to profound losses. Individuals with auditory neuropathy classically show very inconsistent audiometric responses during a test and between tests.
听神经病变（或听觉不同步）可能占儿童听力损失的11% (Rance et al.，1999)。有关这种疾病的信息可以在第13章和第19章找到。由于言语识别非常差，这些孩子中的许多人看起来都有严重的听力障碍。但是，纯音阈值不遵循任何特定模式。这些儿童的纯音听力阈值范围可以从最小值到严重损失。患有听觉神经病变的人通常在同一测试期间与多项测试之间表现出非常不一致的听觉反应。
AGING
老龄化
Presbycusis is a term that describes the gradual loss of hearing sensitivity that occurs in most individuals as they grow older. Studies suggest (Schuknecht, 1974; Dubno et al., 2013) that several different types of damage can occur to the auditory system because of aging. Hearing loss due to aging typically causes a gently sloping, high-frequency sensory/ neural hearing loss that tends to be slightly greater in men than in women. Figure 3.11 shows the average amount of threshold elevation expected based on aging in men who have had limited exposure to intense sounds. Even among this select group of participants, large individual differences are often observed.
老年性聋是一个术语，是用来描述大多数人随着年龄的增长听力敏感度逐渐丧失的术语。研究表明（Schuknecht，1974年；Dubno等人，2013年），由于衰老，听觉系统可能发生几种不同类型的损害。由于年龄增长导致的听力损失通常导致平缓倾斜的高频感觉/神经性听力损失，男性听力损失往往比女性略高。图3.11显示了有限地接触到强烈声音的男性，随着年龄增长，阈值的平均上升幅度。即使在这组被选中的参与者中，也经常观察到巨大的个体差异。
An acoustic tumor (acoustic neuroma/neurinoma or vestibular schwannoma) is a rare disorder. Once identified, these tumors are usually removed surgically, because they can compress the brainstem and threaten life. Early diagnosis and removal lessen the risk of complications during surgery and increase the opportunity to preserve hearing if that approach is pursued.
听神经瘤（听神经瘤/神经鞘瘤或前庭神经鞘瘤）是一种罕见的疾病。一旦确诊，这些肿瘤通常可通过手术切除，因为它们会压迫脑干，威胁生命。早期诊断和切除可以降低手术中并发症的风险，并且可以增加保持听力的机会。
Magnetic resonance imaging (MRI) is the definitive test for acoustic tumors. Unfortunately, it is expensive and only becomes cost effective when a screening test is used to assess which patients should receive an MRI. Puretone audiometry should be considered as part of that screening procedure. When the auditory nerve is compressed by the tumor, it often, but not always (Magdziarz et al., 2000), results in a unilateral or asymmetrical hearing loss. Because the fibers on the outside of the auditory nerve code high frequencies, the hearing loss is associated with the high frequencies (Schlauch et al., 1995). Studies have shown that a screening test that compares the average threshold difference between ears for 1, 2, 4, and 8 kHz is most effective (Schlauch et al., 1995). Threshold differences between ears for this PTA that exceed 15 dB or 20 dB maximize identification of persons with these tumors while minimizing false-positive diagnoses of persons with cochlear losses. The pass–fail criterion (e.g., requiring a 20-dB difference between ears) may differ depending on the money available for follow-up tests. A pass–fail criterion requiring 15-dB or greater differences between ears identifies more tumors than one requiring 20-dB or larger differences, but the smaller difference also yields more false-positive responses. False-positive responses (in this case, persons with cochlear losses identified incorrectly as having tumors) place a burden on the healthcare system, because follow-up tests such as MRI or auditory-evoked potentials are expensive.
磁共振成像（MRI）是听神经瘤的确诊手段。遗憾的是，它很昂贵，并且只有在使用筛选检查评估哪些患者应该接受MRI时才具有成本效益。纯音测听应该被认为是筛选程序的一部分。当听神经被肿瘤压迫时，通常但不总是（Magdziarz et al.， 2000）导致单侧或不对称的听力损失。由于听觉神经外部的神经纤维对高频进行编码，因此听力损失与高频有关（Schlauch et al.，1995）。研究表明，比较1、2、4和8Hz之间的平均阈值差异的筛选检查是最有效的（Schlauch et al.， 1995）。超过15db或20db的PTA的耳间阈值差异可以最大限度地识别这些肿瘤患者，同时最大限度地减少耳蜗损失患者的假阳性诊断。通过-未过标准（例如，要求两耳之间相差20分贝）可能会因后续检查的可用资金而有所不同。两耳间15dB或更大差异的通过-未过标准比两耳间20dB或更大差异的标准能识别更多的肿瘤，但是较小差异也产生更多的假阳性反应。假阳性反应（在这种情况下，耳蜗受损的人被错误地认定为患有肿瘤）给医疗系统带来了负担，因为后续的检查，如核磁共振成像（MRI）或听觉诱发电位（auditor- evpotential），成本高昂。
The effectiveness of a screening test based on the threshold asymmetries between ears is dependent on the clinical population. This test was found to be ineffective in a Veterans Administration hospital where many patients are males who have presbycusis and noise-induced hearing loss (NIHL) (Schlauch et al., 1995). By contrast, preliminary data from young women with normal hearing in their better ear suggest that true-positive rates and false-positive rates for this test are comparable to those for auditory brainstem response (Schlauch et al., 1995). It should also be noted that a small percentage of persons (<3%) with acoustic tumors have no hearing loss or hearing threshold asymmetry (Magdziarz et al., 2000).
基于耳间阈值不对称的筛选试验的有效性取决于临床人群。这项测试在退伍军人管理局医院被发现是无效的，在那里许多患者是男性，他们有老年性耳聋和噪声性听力损失（NIHL）（Schlauch et al.， 1995）。相比之下，来自听力正常的年轻女性的初步数据表明，该测试的真阳性率和假阳性率与听觉脑干反应的真阳性率和假阳性率相当（Schlauch et al.，1995）。还应注意的是，有一小部分（<3%）听神经瘤患者没有听力损失或没有听力阈值不对称（Magdziarz et al.，2000）。
MÉNIÈRE’S DISEASE
梅尼埃病
Ménière’s disease is diagnosed based on the symptoms of sensory/neural hearing loss, vertigo, tinnitus, and aural fullness (Committee on Hearing and Equilibrium, 1995) as well as the exclusion of other known diseases. Adding to the diagnostic challenge, the four symptoms do not occur all at once, and some of them may occur only during the intermittent attacks that characterize this disease. It takes, on average, 1 year after the first symptom occurs before all of the symptoms are experienced by a person stricken with this disease. Ménière’s disease rarely occurs before age 20 and is most likely to begin between the fourth and sixth decades (Pfaltz and Matefi, 1981).
梅尼埃病的诊断依据是感音/神经性听力损失、眩晕、耳鸣和耳闷症状（听力和平衡委员会，1995年），以及排除其他已知疾病。诊断困难的是，这四种症状并不是同时出现的，其中一些症状可能只在这种疾病的间歇性发作期间出现。平均来说，在第一个症状出现后的1年内，患者才能经历到这种疾病的所有症状。梅尼埃病很少发生在20岁之前，最可能发生在40岁至60岁之间。（Pfaltz and Matefi, 1981）
Ménière’s disease usually begins as a unilateral sensory/ neural hearing loss, but the frequency of bilateral involvement increases with disease duration (Stahle and Klockhoff, 1986). Although audiometric configuration is not too helpful in diagnosing Ménière’s disease, a peaked audiogram (described in Table 3.3) is most common (roughly 60% of involved ears), and a rising audiogram is also seen quite frequently, especially in the earliest stages of the disease. However, the peaked audiogram is also seen in 13% of ears with acoustic tumors (Ries et al., 1998).
梅尼埃病通常以单侧感觉/神经性听力损失开始，但随着病程的延长，双侧受累的频率增加（Stahle和Klockhoff，1986）。虽然听力曲线对梅尼埃氏病的诊断没有太大帮助，但峰值听力图（表3.3中描述）是最常见的，而且上升的听力图也很常见（大约占受累耳朵的60%），特别是在疾病的早期阶段。然而，13%的听神经瘤患者的听力图也出现峰值听力图。
NOISE-INDUCED HEARING LOSS AND ACOUSTIC TRAUMA
噪声性聋与声损伤
Exposure to intense sound levels can cause permanent or temporary hearing loss due to hair cell damage. When a narrowband sound is presented at a level high enough to result in damage, a loss occurs at a frequency roughly one-half octave above the frequency of exposure (Henderson and Hamernik, 1995). Most people who are exposed to damaging noise levels in their work or recreational endeavors are exposed to broadband sounds, but their losses, especially during early stages of NIHL, are characterized by a “notch” (a drop in hearing) on the audiogram. The greatest hearing loss typically occurs in the region of 3,000 to 6,000 Hz. The susceptibility of these frequencies is a result of sound amplification by the external ear (Gerhardt et al., 1987). The amplification is mainly a result of the ear canal resonance, which increases the level of sound by 20 dB or more. Temporary hearing loss is referred to as temporary threshold shift (TTS), and permanent changes are referred to as permanent threshold shifts (PTS).
暴露于强烈的声级下可能会由于毛细胞损伤而导致永久性或暂时性听力损失。当窄带声音的音量高到足以造成损坏时，损失的频率大约在曝光频率后面的半倍频程上。大多数在工作或娱乐活动中暴露于破坏性噪音水平的人都会接触到宽带声音，但是他们的损失，特别是在噪声性聋的早期阶段，其特点是听力图上有一个“凹槽”（听力下降）。最严重的听力损失通常发生在3，000至6，000赫兹之间。这些频率的敏感性是外耳放大声音的结果。放大主要是耳道共振的结果，可使声级提高20dB或更多。暂时性听力损失称为暂时性阈移（TTS），永久性改变称为永久性阈移（PTS）。
The greater variability of thresholds at 6 and 8 kHz than at other frequencies makes small noise notches associated with early NIHL difficult to identify. Some frequently used rules for quantifying noise notches can produce high falsepositive rates when decisions are based on a single audiogram (Schlauch and Carney, 2011). Averaging multiple audiograms improves diagnostic accuracy as does clearing the ear canals of all earwax, which can result in the appearance of a high-frequency loss (Jin et al., 2013; Schlauch and Carney, 2012). NIHL can be slowly progressive, as listeners are exposed to high sound levels over months and years (Ward et al., 2000), or it can rapidly change, such as noise trauma after a sudden explosion or impulsive sound (Kerr and Byrne, 1975; Orchik et al., 1987). The shooting of a rifle can result in a greater loss in the ear closest to the muzzle of the gun. In right-handed persons, the left ear is exposed directly to the muzzle, and the right ear is protected from the direct blast by the head. New evidence (Kujawa and Liberman, 2009) suggests that PT thresholds may return to near normal following noise exposure, whereas functional auditory abilities may remain compromised due to the noise exposure. (See Chapter 32 for NIHL.)
在6 kHz和8 kHz的阈值比在其他频率有更大的变异性，使得与早期噪声性聋相关联的小噪声切迹难以识别。当决策基于单个听力图时，一些常用的量化噪声切迹的规则可以产生高的假阳性率（Schlauch和Carney，2011年）。多次听力图的平均值可以提高诊断的准确性，如同清除所有耳道内的耳垢会提高诊断准确性，这些耳垢会导致高频损耗。噪声性聋可以缓慢进展，因为听者在数月或数年的时间里都暴露在高强度的声级中（Ward et al.， 2000），也可以快速变化，例如突然爆炸后或脉冲声的噪音创伤。步枪的射击会使靠近枪口的耳朵损失更大。在惯用右手的人中，左耳直接暴露于枪口，右耳受到头部保护免于直接受到冲击。新的证据显示，在噪声暴露后纯音阈值可能会恢复到接近正常水平，而功能性听觉能力可能会因噪声暴露而仍然受损。（NIHL见第32章。）
OTOTOXICITY
耳毒性
Regular monitoring of PT thresholds is particularly important for patients who take drugs known to be ototoxic. For example, certain powerful antibiotics and cancer-fighting drugs are known to cause cochlear and vestibular damage in many patients. Monitoring hearing sensitivity during treatment could allow a physician to consider alternative treatments that might preserve hearing. Ototoxic drugs typically cause reduction in high-frequency hearing before having any adverse effect on hearing for the speech range. For this reason, extended high-frequency hearing testing is recommended for ototoxic monitoring test protocols. Several studies have demonstrated the effectiveness of early identification of ototoxic hearing loss by monitoring thresholds for frequencies higher than 8,000 Hz (Fausti et al., 1992). However, for ototoxic drugs that selectively damage inner hair cells in the cochlea (e.g., carboplatin), PT thresholds may be unaffected even though extensive damage has occurred (Lobaranis et al., 2013).
定期监测纯音阈值对于服用已知具有耳毒性药物的患者尤为重要。例如，已知某些强效抗生素和抗癌药物会在许多患者造成耳蜗和前庭损伤。在治疗期间监测听力敏感性可让医生考虑可能保留听力的替代治疗。在对言语范围的听力产生任何不利影响之前，耳毒性药物通常会导致高频听力降低。因此，耳毒性监测测试方案中建议对扩展的高频进行听力测试。一些研究已经证明通过监测8,000 Hz以上频率的阈值来早期识别耳毒性听力损失的有效性。然而，对于选择性损害耳蜗内毛细胞的耳毒性药物，即使发生了广泛的损伤，纯音阈值也可能不受影响。
OTITIS MEDIA
中耳炎
Young children are susceptible to temporary, recurring middle-ear inflammations (otitis media) that are often accompanied by fluid in the middle ear (effusion). Otitis media, often referred to as a middle-ear “infection,” may be viral or bacterial but is most often serous (noninfected fluid). Otitis media is the most common medical diagnosis for children, accounting for 6 million office visits in 1990 for children between the ages of 5 and 15 years (Stoll and Fink, 1996). Adults, too, may have otitis media with effusion, although the prevalence decreases significantly with age (Fria et al., 1985). During the active infection, often lasting a month or more, a patient’s hearing loss may fluctuate, usually varying between 0 and 40 dB. The average degree of hearing loss is approximately 25 dB. Figure 3.8, which was used earlier in this chapter to illustrate an audiogram for a conductive loss, shows an audiogram derived from the average thresholds from a group of children diagnosed with otitis media.
幼儿易患暂时性的、反复发作的中耳炎症（中耳炎），中耳炎常伴有中耳积液（积液）。中耳炎，通常被称为中耳“感染”，可能是病毒性或细菌性，但最常见的是浆液性（非感染液体）。中耳炎是儿童最常见的医学诊断，1990年，5 - 15岁儿童共有600万人次就诊（Stoll and Fink, 1996）。成年人也可能患有分泌性中耳炎，尽管其发病率随着年龄的增长而显著下降（Fria et al.，1985）。在感染发作期，通常持续一个月或更长时间，患者的听力损失可能出现波动，通常在0至40分贝之间变化。平均听力损失约为25分贝。图3.8是本章前面用来说明传导性损失的听力图，它显示了一组诊断为中耳炎的儿童的平均阈值。
TYMPANIC MEMBRANE PERFORATIONS
鼓膜穿孔
Tympanic membrane perforations are caused by trauma, disease, or surgery. The diameter and location of perforation and the involvement of other middle-ear structures determine the amount of conductive hearing loss, if any. For instance, a myringotomy and the placement of pressureequalization tubes represent a physician-induced perforation that results in a minimal air–bone gap in successful surgeries.
鼓膜穿孔是由外伤、疾病或手术引起的。如果有的话，穿孔的直径和位置以及其他中耳结构的参与决定了传导性听力损失量的程度。例如，鼓膜切开术和鼓膜置管代表了一种医生诱导的穿孔，在手术成功后会导致最小的气骨间隙。
The measurement of AC thresholds in the presence of tympanic membrane perforations requires special consideration. Figure 3.12 shows an audiogram obtained in a single session from a school-age child who has a tympanic membrane perforation in the left ear and a pressure-equalization tube in the right ear. Thresholds were measured twice in each ear, once with supra-aural earphones and again with insert earphones. Note that the low-frequency thresholds obtained from insert earphones were as much as 15 to 25 dB poorer than the ones obtained with supra-aural earphones. This outcome is typical and is predicted because insert earphones are more susceptible to calibration problems in the presence of perforations than are supra-aural earphones when calibration is based on coupler rather than real ear measurements (Voss et al., 2000). The thresholds obtained using the supra-aural earphones are more accurate in this instance and in any situations in which the effective volume of the ear canal is significantly larger than is typical.
在鼓膜穿孔的情况下，测量纯音阈值需要特殊考虑。图3.12显示了一个学龄儿童在一次治疗中测到的听力图，该儿童左耳有鼓膜穿孔，右耳有鼓膜置管。每只耳朵中测量两次阈值，一次使用压耳式耳机，另一次使用插入式耳机。请注意，从插入式耳机获得的低频阈值比用压耳式耳机获得的低15至25dB。这种结果是典型的并且是可以预测的，因为当校准基于耦合器而不是真耳测量时，插入式耳机比压耳式耳机更容易在穿孔的情况下出现校准问题（Voss等，2000）。在这种情况下以及在任何耳道有效容积明显大于典型的情况下，使用压耳式耳机获得的阈值更准确。
图3.12同一儿童双侧穿孔两种耳机的听力图。
Relation between Puretone Thresholds and Speech Measures
纯音阈值与言语测试的关系
PT thresholds are often compared with speech audiometric test results. The two most common comparisons are with speech reception thresholds (SRT) and suprathreshold word-recognition scores (WRSs). (See Chapter 5 for a comprehensive review of speech audiometry.)
纯音阈值通常与言语听力测试结果进行比较。两个最常见的比较是言语接受阈（SRT）和阈上单词识别率（WRSs）。（有关言语测听的全面回顾，请参见第5章。）
SRTs obtained using spondaic words (or spondees) agree well with PT thresholds for low frequencies. Spondees are easily recognized; listeners only need to recognize the vowels to identify these words correctly. Because of the importance of the vowels at low intensities, spondee thresholds are found to agree closely with the average of PT thresholds for 500 and 1,000 Hz (Carhart and Porter, 1971). In the event of a rising audiogram, better agreement between the spondee and PT thresholds is the average for 1,000 and 2,000 Hz. Spondee thresholds and a two-frequency PTA, as noted earlier, nearly always agree within ±10 dB in cooperative examinees. This agreement makes the threshold for spondaic words an excellent check on the validity and reliability of the audiogram. This comparison is important for most children. It is also a valuable tool for assessing the reliability of PT thresholds in adults who demonstrate inconsistent puretone responses or who may present with pseudohypacusis (Schlauch et al., 1996).
使用扬扬格单词（扬扬格词/双音节词）获得的SRTs与低频纯音阈值一致。扬扬格词很容易识别；听者只需要识别元音就可以正确识别这些单词。由于低强度时元音的重要性，扬扬格词阈值与500和1000 Hz的纯音阈值的平均值非常接近（Carhart and Porter, 1971）。在上升的听力图中，扬扬格词和纯音阈值之间更好的一致性是1000和2000 Hz的平均值。扬扬格词阈值和如前所述的双频PTA在合作参与者中几乎总是在±10dB内一致。这一协议使扬扬格词的阈值对听力图的有效性和可靠性进行了极好的检验。这种比较对大多数孩子都很重要。它也是评估成人纯音阈值可靠性的有价值的工具，这些成人表现出不一致的纯音反应或可能存在伪聋。
Suprathreshold word-recognition performance is assessed in most clinical settings by scoring a client’s ability to repeat back a list of monosyllabic words. WRSs provide a valid estimate of speech understanding ability (Wilson and Margolis, 1983) and quantification of the distortion, if any, caused by sensory/neural hearing loss. WRSs are correlated with puretone audiometric thresholds in persons with cochlear losses (Pavlovic et al., 1986), but individuals’ scores vary considerably depending on the type of damage to the auditory system. If the words are presented at a level high enough to make the speech sounds audible (overcoming the attenuation caused by the loss), persons with mild cochlear hearing loss are expected to have high WRSs, and those with severe to profound losses are likely to have fairly low scores. Dubno et al. (1995) and Yellin et al. (1989) have published tables relating WRSs and the average of PT thresholds for 500, 1,000, and 2,000 Hz for groups of persons with typical cochlear losses. WRSs that are abnormally low for a given PTA are associated with a variety of conditions including an acoustic tumor, multiple sclerosis, Ménière’s disease, auditory neuropathy, and cochlear dead regions (Moore, 2004), to name a few. When there are dead regions (areas of missing inner hair cells in the cochlea), PT thresholds may appear artificially better than expected because of the spread of energy along the cochlea. Healthier cochlear cells adjacent to the missing cells will elicit a response to puretones presented at the dead region frequency.
在大多数临床环境中，阈上单词识别性能是通过对患者重复单音节单词的能力来评估的。WRSs提供了对言语理解能力的有效评估（Wilson and Margolis, 1983），并量化了由感音神经听力损失引起的失真 （如果有的话）。WRS与耳蜗损伤者的纯音听阈相关（Pavlovic et al., 1986），但个体的分数因听觉系统损伤类型的不同而有很大差异。如果这些单词音量足够高，使语音可以听到（克服了损耗引起的衰减），那么轻度耳蜗听力损失的人预计会有较高的WRSS，而重度至极重度损失的人可能会有相当低的分数。Dubno et al.，（1995）和Yellin et al.（1989）发表了关于典型耳蜗损伤人群WRSs与500、1000、2000 Hz纯音阈值平均值关系的表。对于给定PTA而言，异常低的WRSs与多种疾病有关，包括听神经肿瘤、多发性硬化症、梅尼埃病、听神经病变和耳蜗死区等等（Moore，2004）。当存在死区（耳蜗内毛细胞缺失的区域）时，由于能量沿着耳蜗的扩散，纯音阈值可能比预期的要高。与缺失细胞相邻的健康耳蜗细胞会对死区频率的纯音作出响应。
Automated Audiometry
自动听力测定
Clinical researchers automated the measurement of routine hearing thresholds to increase clinical efficiency (Rudmose, 1963). Devices were developed for this purpose, and several machines were manufactured and sold commercially. Some of these automated audiometers had the ability to vary intensity and frequency during a hearing test.
临床研究人员自动化了常规听力阈值的测量以提高临床效率（Rudmose, 1963）。为此研制了一些设备，制造了几台机器并进行了商业销售。其中一些自动测听仪能够在听力测试中改变强度和频率。
The Bekesy audiometer is an automated audiometer that was a common piece of equipment in major clinical and research settings in the 1960s. In its routine application, AC thresholds were assessed for interrupted tones and sustained tones for frequencies ranging from 100 to 10 kHz. Frequencies were swept through the range over time, typically at a rate of one octave per minute. The examinee controlled the level of the sound by depressing a handheld switch for as long as he or she heard a tone and released it when none was heard. The resulting brackets around threshold were recorded on an audiogram. Patterns of responses for sustained tones and interrupted tones were found to distinguish between different etiologies of hearing loss (see Chapter 33 on pseudohypacusis). In recent years, the use of Bekesy audiometry has decreased in medical settings, but it still has important applications in research, the military, and in hearing conservation programs.
贝克西（Bekesy）听力计是一种自动化听力计，20世纪60年代主要临床和研究环境中的常用设备。在它的常规应用中，100-10khz的中断音调和持续音调作为气导阈值评估。频率在一段时间内扫过整个范围，通常以每分钟一个倍频程的速度扫过。受检者只要听到一种声音，就按下手持开关来控制音量，当听不到时，就释放控制开关。由此产生的阈值被记录在听力图上。持续音调和间断音调的反应模式被发现可以区分听力损失的不同病因（见第33章关于伪聋）。近年来，贝克西听力计在医学环境中的使用有所减少，但在研究，军队和听力保护项目中仍有重要应用。
Within the past few years, a new generation of automated audiometers has been developed (Margolis et al., 2010). The new automated audiometers are capable of measuring masked AC and BC thresholds, as well as WRSs, with only a single placement of the earphones and BC oscillator. Bekesy audiometry is still used along with some other automated methods (Laroche and Hetu, 1997), including ones that implement the threshold-finding procedure used in manual puretone audiometry (Margolis et al., 2010). Computer- based rules control the presentation of stimuli, examinee responses, and the plotting of thresholds. The goal is to automate threshold collection for routine cases, which will free audiologists to perform more complex measures or to work with difficult-to-test populations.
在过去的几年里，新一代的自动测听仪已经开发出来（Margolis et al.，2010）。新的自动测听仪能够测量掩蔽的气导和骨导阈值，以及WRSs，只需要放置一个耳机和骨导振荡器。贝克西听力计仍然与其他一些自动化方法一起使用（Laroche and Hetu, 1997），包括实现手工纯音测听中使用的阈值查找程序的方法（Margolis et al.， 2010）。基于计算机的规则控制刺激的呈现、受试者的反应和阈值的绘制。目标是自动收集常规病例的阈值，这将使听力学家得以执行更复杂的测量，或与测试困难的人工作。
Calibration
校准
Clinical data require accurate stimulus specification, or the results are meaningless. When most persons think of calibration of audiometers, the obvious examples include the accuracy of puretone frequency and level. However, puretone calibration involves much more, including an assessment of attenuator linearity, harmonic distortion, rise and fall times, and more. Consult ANSI (2010) and Chapter 2 on calibration in this book to learn more about this topic.
临床数据需要精确的刺激指标，否则结果毫无意义。当大多数人想到听力计的校准时，最明显的例子包括纯音频率和音量的准确性。然而，纯音校准涉及更多，包括衰减器线性度，谐波失真，上升和下降时间等的评估。有关此主题的更多信息，请参阅ANSI（2010）和本书中有关校准的第2章。
Puretone Thresholds and the Audiologic Test Battery
纯音阈值与听力测试组合
PT thresholds are measured on nearly everyone entering a diagnostic audiology clinic, but the test sequence and the extent of the measurements often differ across clinics. Most of these differences in protocol are implemented to save testing time, which contributes to the cost of running a clinic. ASHA’s guide to manual PT threshold audiometry (2005) makes no recommendation concerning the puretone test sequence. In 2000, the Joint Audiology Committee on Practice Algorithms and Standards recommended an algorithm that listed puretone AC testing (with appropriate masking applied) followed by puretone BC testing with appropriate masking. They acknowledged that the assessment process may vary “based on patient need and the assessment setting.” Furthermore, they stated that “decision-making . . . occurs(s) throughout this process.”
纯音阈值是几乎所有进入听力学诊所就诊的患者都要测量的，但是测试顺序和测量的范围往往因诊所而异。这些协议上的差异大部分是为了节省测试时间而实现的，这有助于节省诊所的运营成本。ASHA的人工纯音阈值测试指南（2005）对纯音测试顺序没有给出任何建议。2000年，实践算法和标准联合听力委员会建议采用一种算法，列出纯音气导测试 （应用适当的掩蔽），然后使用适当的掩蔽方法进行纯音骨导测试。他们承认，评估过程可能会根据“病人的需要和评估环境”而有所不同。此外，他们还说“决策……在整个过程中发生。”
Based on informal surveys of clinicians in a variety of settings, it seems that there is considerable variability in test protocols among clinics. In many clinics, BC thresholds are not usually obtained from persons with normal AC thresholds (near 0 dB HL) unless the case history or risk of middle-ear problems suggests otherwise. BC threshold testing is also omitted in some clinics for returning patients with pure sensory/neural losses if their AC thresholds match those of the prior visit. A common alternative test sequence is to begin with puretone AC thresholds followed by suprathreshold word-recognition testing. After word-recognition testing, BC thresholds are measured. Although it would be useful to have puretone BC thresholds prior to AC thresholds to know how much masking noise can be presented safely, this advantage is outweighed by the inconvenience of having to enter the booth multiple times to reposition the BC vibrator and earphones. Valid, masked AC thresholds can be obtained successfully from most clients before obtaining BC thresholds.
根据在不同环境下对临床医生的非正式调查，各诊所之间的测试方案似乎存在相当大的差异。在许多诊所中，骨导阈值通常不是从具有正常气导阈值（接近0 dB HL）的人获得的，除非有中耳问题相关病史或风险。在一些诊所，单纯感音/神经性损失的患者如果其气导阈值与之前的检查值相匹配，那么骨导阈值测试会被省略。一种常见的替代测试顺序是从纯音气导阈值开始，然后进行阈上单词识别测试。经过单词识别测试，测得骨导阈值。虽然在气导阈值之前设置纯音骨导阈值会很有用，以了解多少掩蔽噪声是安全的，但这一优势被不得不多次进入测听室重新定位骨导振动器和耳机的不便所抵消。有效的、掩蔽的气导阈值可以在得到骨导阈值之前从大多数测试者那里成功获取。
A few clinics begin with immittance testing, which usually includes a tympanogram and acoustic reflex thresholds. If the case history does not indicate a middle-ear problem and these tests of middle-ear function are normal, then BC thresholds may not be performed, and the loss, if present, is assumed to be a sensory/neural loss. A possible risk of this strategy is that, in rare instances, persons with middle-ear problems have normal immittance measures. In this situation, a conductive loss would be missed. This approach also adds the expense of immittance testing for each client. Studies should be done using an evidence-based practice model to determine whether the assessment of middle-ear status of each client using immittance or wideband reflectance (see Chapter 9) is justified. Another time-saving strategy might be to measure BC thresholds at two frequencies, a low and a high frequency, and if an air–bone gap is not observed, BC thresholds are not measured for other frequencies. A low frequency, such as 500 Hz, would assess stiffness-related middle-ear pathologies. A high frequency, such as 4,000 Hz, would identify mass-related middle-ear pathologies and collapsed canals. Since this method requires placement of the BC vibrator, the amount of time actually saved would be limited.
一些诊所从导抗测试开始，通常包括鼓室图和声反射阈值。如果病史没有提示中耳问题，并且中耳功能测试正常，则可能不再进行骨导阈值测试，如果出现听力下降，则假定为感音/神经性损失。这种方法的一个可能风险是，在极少数情况下，有中耳问题的人具有正常的导抗测试值。在这种情况下，传导性损失会被忽略。这种方法还增加了每个受试者的导抗测试费用。应使用基于证据的实践模型进行研究，以确定是否使用导抗或宽带反射评估每个患者的中耳状态（见第9章）。另一种节省时间的策略可能是在两个频率测量骨导阈值，一个低频率和一个高频率，如果没有观察到气骨间隙，则不会测量其他频率的骨导阈值。低频（如500hz）可评估与硬化有关的中耳病变。高频，例如4000赫兹，可以识别与肿块有关的中耳病变和耳道塌陷。由于此方法需要放置骨导振子，所以实际节省的时间是有限的。
Despite the observed variability, it seems that it is possible for audiologists to obtain important diagnostic information about the degree, type, and configuration of hearing losses using a variety of valid, evidence-based puretone audiometric methods. Although at first glance, the puretone test procedure may appear elementary, it is clear that well-informed test procedures using appropriate and calibrated test equipment provide a necessary part of the complete audiologic test battery and form the basis for clinical decision making.
尽管存在观察变异性，但听力学家似乎可以使用各种有效的、基于证据的纯音听力测定方法获得关于听力损失的程度、类型和配置的重要诊断信息。虽然乍一看，纯音测试程序可能很基础，但很明显，采用适当和校准的测试设备进行的测试提供了完整的听力测试组合的必要部分，并形成临床决策的基础。
FOOD FOR THOUGHT
引人深思的事
Given the known test–retest variability of PT thresholds, what is the threat to the quality of a hearing conservation program if the tester chooses not to make multiple estimates of baseline audiograms?
1． 鉴于纯音阈值的已知测试重测变异性，如果测试人员选择不对基线听力图进行多次评估，对听力保护程序的质量有何威胁？
Think about examples of auditory pathology where the PT threshold might be misleading, when it might not reflect the full nature of the underlying cochlear injury.
思考下听觉病理学的例子，其中纯音阈值可能具有误导性，而纯音阈值可能不会反映潜在耳蜗损伤的全部性质。
Consider several cases where the ear canal volume (the volume under the earphone) might significantly affect the resulting PT threshold. Consider the client’s total volume of the outer ear, perforations of the eardrum, and possible occlusions in the ear canal. What effect will these have on the resulting thresholds?
Chapter3 Puretone Evaluation
纯音评估
INTRODUCTION
简介
Most people who attend primary school in the United States and in other industrialized nations experience puretone* testing firsthand as a method to screen for hearing loss. Puretone threshold testing is seen in films, such as Woody Allen’s award-winning movie Hannah and Her Sisters or the film Wind Talkers. These casual experiences with audiology may give lay people the false impression that audiology is a narrow profession.
在美国和其他工业化国家，大多数上小学的人都经历过纯音测试，而纯音测试是一种筛选听力损失的方法。纯音阈值测试可以在电影看到，比如伍迪·艾伦的获奖电影《汉娜和她的姐妹们》或者电影《风语者》。这些与听力学有关的偶然经历可能会给外行人一个错误的印象，即听力学是一个狭窄的职业。
*The use of the compound noun “puretone” is the editor’s choice for consistency purposes.
复合名词“puretone”的使用是编辑出于一致性目的而选择的。
Most audiologists would likely agree that puretone (PT) thresholds represent a key component of the assessment battery. Proper administration and interpretation of PT threshold tests require considerable knowledge, as it is not always simple and straightforward. The goal of this chapter is to introduce readers to the complexity of PT threshold testing, as well as to provide clinicians with a reference for clinical applications.
大多数听力学家可能会同意纯音（PT）阈值是评估组块的一个关键组成部分。纯音阈值测试的正确使用和解释需要大量的知识，因为它并不总是简单和直接的。本章的目的是向读者介绍纯音阈值测试的复杂性，并为临床医师提供临床应用参考。
WHAT ARE PURETONES AND HOW ARE THEY SPECIFIED?
什么是纯音，它们是如何定义的？
PT thresholds represent the lowest level of response to a tonal stimulus. Puretones are the simplest of sounds described by their frequency, amplitude, phase, and duration. The most important of these characteristics for puretone audiometry are frequency and amplitude (or intensity level).
纯音阈值是对音调刺激最低响应级别的表示。纯音是根据频率、振幅、相位和持续时间来描述的最简单的声音。这些特征中对于纯音测听来说最重要的是频率和振幅（或强度级别）。
Puretone frequency is perceived as pitch, the characteristic of sound that determines its position on a musical scale. Young people with normal hearing are able to perceive frequencies between 20 and 20,000 Hz. Human hearing is more sensitive (better) in the range of frequencies between 500 and 8,000 Hz than it is at either extreme of the audible range of frequencies. Conventional puretone audiometry typically assesses thresholds for frequencies between 250 (or 125) and 8,000 Hz. The frequency range for conventional audiometry is very similar to the range of frequencies (100 to 6,000 Hz) that is important for speech understanding (French and Steinberg, 1947).
纯音频率被视为音高（音调），声音的特性决定了它在音阶中的位置。听力正常的年轻人能够感知20到20000赫兹之间的频率。人类的听觉在500到8000赫兹的频率范围内比在可听频率范围的任一极端都更灵敏（更好）。传统的纯音测听通常评估频率在250（或125）到8000赫兹之间的阈值。传统测听的频率范围非常相似对语音理解很重要的频率范围（100到6000 Hz）（French and Steinberg, 1947）。
Puretone amplitude or level is usually quantified in decibels. Decibels (dB) represent the logarithm of a ratio of two values; the term is meaningless without a reference. Two commonly used decibel scales are sound pressure level (SPL) and hearing level (HL). The reference level for dB SPL is 20 μPa, a pressure value. This reference value for SPL was selected to correspond to the faintest pressure that is audible in the frequency region where hearing is most sensitive. The frequency is not specified in the reference level for dB SPL; all sounds expressed in units of dB SPL share the same reference of 20 μPa. The SPL scale is frequently used in audiology to compare the level of speech or other sounds at different frequencies. Such comparisons are critical for prescribing and evaluating hearing aids. HL, a second decibel scale, is used to plot an audiogram, the accepted clinical representation of puretone thresholds as a function of frequency. The reference for dB HL is the median threshold for a particular frequency for young adults with no history of ear problems. Unlike dB SPL, the zero reference level for dB HL varies with frequency, because humans have more sensitive hearing at some frequencies than others. Because the reference is normal human hearing, thresholds that deviate from 0 dB HL at any frequency show how much one’s hearing deviates from this normal value.
纯音的振幅或音量通常用分贝表示。分贝（dB）表示两个值之比的对数；没有参考，这个术语就没有意义。两种常用的分贝标度是声压级（SPL）和听力级（HL）。dB SPL的参考音量是20μPa，一个压力值。SPL的这个参考值是根据听觉最敏感的频率区域所能听到的最微弱的压力来选择的。dB SPL参考音量未指定频率；所有以dB SPL为单位表示的声音共享相同的参考20μPa。SPL测量在听力学中经常用来比较不同频率下的语音或其他声音的水平。这种比较对于开处方和评估助听器至关重要。HL是第二种分贝标度，用于绘制听力图，纯音阈值作为频率函数的公认临床表现。dB HL的参考值是一个特定频率的中值阈值，适用于没有耳部病史的年轻人。与dB SPL不同，dB HL的零参考水平随频率变化，因为人类在某些频率下的听力比其他频率更灵敏。因为参考的是正常人的听力，在任何频率上偏离0 dB HL的阈值显示了一个人的听力偏离这个正常值的程度。
Figure 3.1 illustrates thresholds displayed in dB SPL and dB HL. The left panel shows hearing thresholds plotted in dB SPL as a function of frequency. Thresholds plotted in this way constitute a minimum audibility curve. The right panel shows a conventional audiogram plotted in dB HL. Note that on the dB SPL scale, larger decibel values are plotted higher on the graph. By contrast, larger values in dB HL are plotted lower on the audiogram. To illustrate the relationship between dB SPL and dB HL, the reference values for 0 dB HL (average normal hearing) for a specific earphone are plotted in dB SPL as a solid line. Illustrated with a dashed line on these same two figures are the thresholds for a person with a high-frequency hearing loss. Note in the figure on the left that the separation between the solid line and the dashed line represents values for dB HL on the audiogram.
图3.1显示了以dB SPL和dB HL显示的阈值。左图显示以dB SPL绘制的听力阈值作为频率的函数。以这种方式绘制的阈值构成最小可听曲线。右图显示了以dB HL绘制的传统听力图。请注意，在dB SPL标度上，较大的分贝值在图表上绘制得更高。相比之下，在听力图上较大的dB HL值被绘制得较低。 为了说明dB SPL和dB HL之间的关系，将特定耳机的0 dB HL（平均正常听力）的dB SPL参考值绘制为实线。在这两个图中用虚线表示的是高频听力损失的人的阈值。请注意，左侧图中实线和虚线之间的间隔表示听力图上dB HL的值。
图3.1：以dB声压级（SPL；左图）和dB听力级别（HL；右图）的阈值与频率的函数关系图。实线代表平均正常听力；虚线表示具有高频听力损失的人的阈值。
WHY PURETONE THRESHOLDS?
为什么是纯音阈值？
The reader might be wondering why audiologists use puretones at specific frequencies when the most meaningful stimulus is speech. Two important reasons are that PT thresholds provide information about the type of hearing loss, as well as quantify frequency-specific threshold elevations that result from damage to the auditory system.
读者可能想知道，为什么听力学专家在特定频率使用纯音，而最有意义的刺激是语音。 两个重要原因是纯音阈值提供了有关听力损失类型的信息，并且量化了由听觉系统受损导致的特定频率阈值升高多少。
PT thresholds provide quantification of amount of loss due to problems with the outer and middle ear (the conductive system) separately from the cochlea and the auditory nerve (the sensory/neural system). This distinction helps in the diagnosis and guides audiologists and physicians with important details for providing treatment strategies.
纯音阈值提供了外耳和中耳（传导系统）不同于耳蜗和听神经（感音/神经系统）所导致的损失量的量化。这种区别在诊断和指导方面有助于为听力师和医生提供有关治疗策略的重要细节。
Damage to the auditory system often results in a loss of sensitivity that is frequency specific. For instance, changes in the stiffness and mass properties of the middle ear affect the relative amount of loss in the low and high frequencies (Johanson, 1948). For air-conduction thresholds, an increase in stiffness results in a greater low-frequency loss, whereas an increase in mass results in a greater loss in the high frequencies. Thresholds for puretones (or other narrowband sounds) also provide us with diagnostic information about the integrity of different channels in the sensory/neural pathway. The auditory system is organized tonotopically (i.e., a frequency-to-place mapping) from the cochlea to the cortex. The tonotopic organization of the cochlea is a result of the frequency tuning of the basilar membrane, with high frequencies represented at the basal end and low frequencies at the apical end. Damage to sensory cells of the cochlea at a specific place along the basilar membrane can result in a loss of hearing that corresponds to the frequencies coded by that place. For this reason, PT threshold tests provide details that would otherwise remain unknown if a broadband stimulus such as speech were used.
听觉系统的损伤通常会导致特定频率的灵敏度下降。例如，中耳硬度和质量特性的变化会影响低频和高频的相对损失量（Johanson, 1948）。对于空气传导阈值，硬度的增加导致更大的低频损耗，而质量的增加导致更大的高频损耗。纯音（或其他窄带声音）的阈值也为我们提供了关于感音/神经通路中不同通道完整性的诊断信息。听觉系统是从耳蜗到皮质的以拓扑方式组织的（即，频率到位置的映射）。耳蜗的拓扑组织是基底膜频率调谐的结果，在基底端表现为高频，在顶端表现为低频。耳蜗基底膜上某一特定位置的感觉细胞受损，会导致与该位置编码频率相对应的听力的丧失。由于这个原因，纯音阈值测试提供了一些细节，如果使用语音等宽带刺激，这些细节将不得而知。
In addition to providing audiologists with critical diagnostic information about the amount and type of loss, PT thresholds find applications (1) for estimating the degree of handicap, (2) as a baseline measure for hearing conservation programs, (3) for monitoring changes in hearing following treatment or progression of a disease process, (4) for screening for hearing loss, (5) for determining candidacy for a hearing aid or a cochlear implant, and (6) for selecting the frequency-gain characteristics of a hearing aid. PT thresholds also provide a reference level for presentation of suprathreshold speech testing and for the meaningful interpretation of other audiologic tests, such as evoked otoacoustic emissions and acoustic reflex thresholds. PT thresholds are also used to assess the functional attenuation of hearing protection devices.
除了向听力师提供关于损失数量和类型的关键诊断信息之外，纯音阈值还应用于：（1）评估残障的程度，（2）作为听力保护计划基线测量，（3）用于监测治疗或疾病进展后的听力变化，（4）听力损失的筛查，（5）确定助听器或人工耳蜗的候选资格，（6）选择助听器的频率增益特性。纯音阈值还为阈上语音测试的呈现提供了参考，并为其他听力测试（如诱发耳声发射和声反射阈值）的有意义解释提供了参考。纯音阈值也被用来评估听力保护装置功能的衰减。
TUNING FORK TESTS
音叉试验
A struck tuning fork produces a sustained puretone that decays in level over time. Unlike an audiometer, tuning forks cannot present a calibrated signal level to a listener’s ear. Despite this shortcoming, tuning fork tests provide qualitative information that can help determine whether a hearing loss is conductive or sensory/neural. Tuning fork tests are promoted by some as an important supplement to puretone audiometry. In a recently published book, otologists are advised to include tuning fork tests as an integral part of the physical examination for conductive hearing loss(Torres and Backous, 2010).
被敲击的音叉产生持续的纯音，其音量会随着时间的推移而衰减。与听力计不同，音叉不能向听者耳朵提供经过校准的信号。尽管有这个缺点，音叉测试提供的定性的信息可以帮助确定听力损失是传导性的还是感音/神经性的。一些人提倡使用音叉测试作为纯音测听的重要补充。在最近出版的一本书中，耳科医生被建议将音叉测试纳入传导性听力损失的体检中（Torres and Backous, 2010）。
The two best known tuning fork tests are the Weber and Rinne. Judgments about the type of hearing loss are made by comparing the pattern of results on both tests. Air conduction (AC) is tested by holding the tuning fork at the opening of the ear canal, and bone conduction (BC) is tested by placing the tuning fork on the mastoid process (the bony area behind the pinna) or on the forehead or incisors (British Society of Audiology, 1987). For the Weber test, a client judges whether sound is perceived in one or both ears when the tuning fork is placed on the forehead. For the Rinne test, the client judges whether sound is louder when presented by AC or by BC. Ideally, conductive hearing losses produce a pattern of responses that is uniquely different from the one for sensory/neural hearing losses. In the Weber, the sound is lateralized to the poorer ear with a conductive loss and to the better ear for a sensory/neural loss. In the Rinne, the sound is louder by BC in a conductive loss and by AC with a sensory/neural loss.
最著名的两个音叉试验是韦伯试验和林纳试验。通过比较两种测试结果来判断听力损失的类型。空气传导（AC）通过将音叉放在耳道口进行测试，骨传导（BC）通过将音叉放在乳突（耳廓后的骨质区域）或前额或门牙上进行测试（英国听力学学会，1987）。在韦伯测试中，当音叉放在前额上时，受试者判断是单耳还是双耳感知到声音。在林纳试验中，受试者判断是AC还是BC感知的声音更大。理想情况下，传导性听力损失会产生一种不同于感官/神经性听力损失的反应模式。在韦伯试验中，在传导性聋中声音偏向差耳，在感音/神经性聋中偏向好耳。林纳试验中，在传导性损失下，骨导感知的声音更大，在感觉/神经性损失下，气导感知的声音更大。
Some recommend tuning fork tests to check the validity of audiograms (Gabbard and Uhler, 2005) or to confirm the audiogram before conducting ear surgery (Sheehy et al., 1971). However, it is important to recognize that tuning fork tests administered to people with known conductive losses have shown that these procedures are often inaccurate (Browning, 1987; Snyder, 1989). Although only about 5% of people with normal hearing or sensory/neural losses are falsely identified as having conductive losses with the Rinne test, this test misses many people with significant conductive losses (Browning, 1987), including 50% of losses that have 20-dB air–bone gaps. The Weber test fares equally poorly. Browning (1987) reports that a majority of children with conductive losses give inappropriate responses on the Weber test. From these and other studies, one must conclude that tuning fork tests are not a replacement or even a supplement to audiometry. Audiometry is capable of identifying nearly 100% of air–bone gaps, as small as 15 dB.
有人建议使用音叉试验来检查听力图的有效性（Gabbard and Uhler, 2005），或者在进行耳外科手术前确认听力图的有效性（Sheehy et al.， 1971）。然而，重要的是要认识到，对已知传导性损伤的人进行的音叉试验表明，这些往往是不准确的（Browning, 1987;斯奈德,1989）。虽然只有大约5%的听力正常或感觉/神经损失的人通过林纳试验被错误地识别为传导性损失，但是这个测试遗漏了许多有显著传导性损失的人（Browning, 1987），包括其中50%的有20分贝气骨间隙的损失。韦伯试验的表现同样糟糕。Browning（1987）报告说，在韦伯试验中，大多数有传导性损失的儿童给出了不恰当的反应。从这些研究和其他研究中，我们必须得出这样的结论：音叉试验不是听力测试的替代品，甚至不是它的补充。听力测定能够识别几乎100%的气骨间隙，最小可达15分贝。
PURETONE AUDIOMETRY
纯音测听
Audiometers are used to make quantitative measures of AC and BC PT thresholds. AC thresholds assess the entire auditory pathway and are usually measured using earphones. When sound is delivered by an earphone, the hearing sensitivity can be assessed in each ear separately. BC thresholds are measured by placing a vibrator on the skull, with each ear assessed separately, usually by applying masking noise to the nontest ear. The goal of BC testing is to stimulate the cochlea directly, thus bypassing the outer and middle ears. A comparison of AC and BC thresholds provides separate estimates of the status of the conductive and sensory/neural systems. If thresholds are elevated equally for sounds presented by AC and BC, then the outer and middle ear are not contributing to a hearing loss. By contrast, if thresholds are poorer by AC than by BC, then the source of at least some of the loss is the outer or middle ear. Figure 3.2 illustrates the AC and BC pathways and how hearing thresholds are typically affected by damage to these structures. See Chapter 4 for a complete review of BC assessment.
听力计用于定量测量空气传导和骨传导纯音阈值。空气传导阈值评估整个听觉通路，通常使用耳机测量。当通过耳机发出声音时，可以分别在每只耳朵中评估听觉灵敏度。骨传导阈值通过在颅骨上放置振动器来测量，每个耳朵单独评估，通常是通过对非测试耳施加掩蔽噪声来测量。骨传导测试的目标是直接刺激耳蜗，从而绕过外耳和中耳。空气传导和骨传导阈值的比较提供了对传导和感音/神经系统状态的分别评估。如果空气传导和骨传导所呈现的声音阈值同等升高，则外耳和中耳不会导致听力损失。相反，如果空气传导的阈值比骨传导的阈值更差，那么至少一些损失来自外耳或中耳。图3.2显示了空气传导和骨传导通路以及听力阈值如何受到这些结构损伤的影响。有关骨传导评估的完整回顾，请参见第4章。
FIGURE 3.2 Conductive and sensory/ neural pathways. (Adapted from Martin (1994))
图3.2传导通路和感觉/神经通路。（改编自Martin (1994)）
Equipment
设备
AUDIOMETERS
听力计
Puretones are generated within an audiometer. Audiometers have the ability to select tonal frequency and intensity level and to route tones to the left or right earphone. All audiometers also have an interrupter switch that presents the stimulus to the examinee. The American National Standards Institute (ANSI) Specification for Audiometers (ANSI, 2010) describes four types of audiometers, with Type 1 having the most features and Type 4 having the fewest features. A Type 1 audiometer is a full-featured diagnostic audiometer. A Type 1 audiometer has earphones, bone vibrator, loud speakers, masking noise, and other features. A Type 4 audiometer is simply a screening device with earphones, but none of the other special features.
纯音是在听力计中产生的。听力计能够选择音调频率和强度级别，并将音调传送到左耳机或右耳机。所有听力计也有一个断续开关，向受检者提供刺激。美国国家标准协会（ANSI）中听力计的规范（ANSI，2010年）描述了四种类型的听力计，类型1功能最多，类型4功能最少。1型听力计是一种功能齐全的诊断听力计。1型听力计具有耳机、骨振动器、扬声器、掩蔽噪音和其他功能。4型听力计只是一种带有耳机的筛选设备，不具有其他特殊功能。
Type 1 (full-featured, diagnostic audiometer) has the ability to assess puretone AC thresholds for frequencies ranging from 125 to 8,000 Hz and BC thresholds for frequencies ranging from 250 to 6,000 Hz. If an audiometer has extended high-frequency capability, air-conduction thresholds can be extended to 16,000 Hz. Maximum output levels for AC testing are as high as 120 dB HL for frequencies where hearing thresholds are most sensitive. By contrast, distortion produced by bone oscillators at high intensities limits maximum output levels for BC thresholds to values nearly 50 dB lower than those for AC thresholds for the same frequency.
类型1（功能齐全的诊断听力计）能够评估125至8000 Hz频率的纯音气导阈值和250至6000 Hz频率的骨导阈值。如果听力计具有扩展的高频能力，则气导阈值可以扩展到16,000 Hz。 在听力阈值最敏感的频率范围内，气导测试的最大输出水平高达120 dB HL。相比之下，骨振动器在高强度下产生的失真将骨导阈值的最大输出限制在比相同频率下气导阈值的输出低近50 dB。
TRANSDUCERS
换能器
Earphones
耳机
Earphones are generally used to test puretone AC thresholds. A pair of supra-aural earphones is illustrated in Figure 3.3. For decades, supra-aural earphones, ones in which the cushion rests on the pinna, were the only choice for clinical audiology. The popularity of supra-aural phones was mainly due to their ease of calibration and the lack of other types of commercially available earphones. In the past few years, insert earphones and circumaural earphones have become available and provide some useful applications for puretone assessment.
耳机通常用于测试纯音气导阈值。图3.3显示了一对压耳式耳机。几十年来，压耳式耳机（耳垫放在耳廓上）是临床听力学的唯一选择。压耳式耳机之所以受欢迎，主要是因为它们易于校准，而且缺乏可商用的其他类型耳机。在过去的几年中，插入式耳机和耳罩式耳机已经面世，并应用于纯音评估。
图3.3 TDH-49型，一种压耳式耳机
Insert earphones are coupled to the ear by placing a probe tip, typically a foam plug, into the ear canal. The commercially available model that has a standardized calibration method for audiology is the Etymotic model ER-3A, which is illustrated in Figure 3.4. These earphones have gained popularity in the past few years because they offer distinct advantages over supra-aural earphones. One major advantage is that insert earphones yield higher levels of interaural attenuation than supra-aural earphones (Killion and Villchur, 1989). Interaural attenuation represents the decibel reduction of a sound as it crosses the head from the test ear to the nontest ear. The average increase in interaural attenuation is roughly 20 dB. This reduces the need for masking the nontest ear and decreases the number of masking dilemmas, situations for which thresholds cannot be assessed, because the presentation level of the masking noise is possibly too high. (See Chapter 6 for a comprehensive review of masking.) Another important advantage of insert earphones over supra-aural earphones is lower test–retest variability for thresholds obtained at 6 and 8 kHz; variability for other frequencies is comparable. Given that thresholds for 6 and 8 kHz are important for documenting changes in hearing due to noise exposure and for identifying acoustic tumors, lower variability should increase the diagnostic precision. A third advantage that insert earphones offer is elimination of collapsed ear canals (Killion and Villchur, 1989). In about 4% of clients, supra-aural earphones cause the ear canal to narrow or be closed off entirely when the cushion presses against the pinna, collapsing the ear canal (Lynne, 1969), resulting in false hearing thresholds, usually in the high frequencies (Figure 3.5) (Ventry et al., 1961). Because insert earphones keep the ear canal open, collapsed canals are eliminated. A fourth advantage of insert earphones is that they can be easily used with infants and toddlers who cannot or will not tolerate supra-aural earphones. A fifth advantage of insert earphones is the option of conducting middle-ear testing and otoacoustic emission testing without changing the earphones; some recently introduced diagnostic instruments use this approach. Although insert earphones offer a hygienic advantage over supra-aural earphones, because the foam tips that are placed into a client’s ear canal are disposable, the replacement cost of those tips is prohibitive for many applications. In addition to higher costs, insert earphones also yield errant thresholds in persons with eardrum perforations, including pressure-equalization tubes (Voss et al., 2000). (See Figure 3.12 for additional information about perforations.) Insert earphones also have maximum output levels that are lower than those produced by supra-aural earphones for some frequencies. Because of these differences, many diagnostic clinics keep both earphone types on hand and switch between them depending on the application.
插入式耳机通过将探头尖端（通常是泡沫塞）插入耳道与耳朵相连。通过听力学标准化校准方法的市售模型是etymotic模型ER-3a，如图3.4所示。这种耳机在过去几年里很受欢迎，因为它们比压耳式耳机有明显的优势。一个主要优点是插入式耳机比压耳式耳机具有更高的耳间衰减（Killion和Villchur，1989年）。耳间衰减代表声音从测试耳穿过头部到非测试耳时的分贝衰减。耳间衰减平均增加约20dB。这减少了掩蔽非测试耳朵的需求，并减少了掩蔽困境的数量，这种困境是无法评估阈值的情况，因为掩蔽噪声程度可能太高。（有关掩蔽的全面回顾，请参阅第6章。）。与压耳式耳机相比，插入式耳机的另一个重要优点是，在6k和8 kHz处测得的阈值的复测变异性较低；其他频率的变异性的可比较的。鉴于6和8 kHz的阈值对于记录噪声暴露引起的听力变化和识别听神经瘤非常重要，较低的变异性可提高诊断精度。插入耳机提供的第三个优点是消除耳道塌陷（Killion和Villchur，1989年）。在约4%的试验者中，当耳垫压在耳廓上时，压耳式耳机会导致耳道狭窄或完全关闭，使耳道塌陷（Lynne，1969），从而导致错误的听力阈值，通常为高频（图3.5）（Ventryet al.，1961）。由于插入耳机使耳道保持开放，从而消除了耳道塌陷。插入式耳机的第四个优点是，它可以很容易用于不能或不愿忍受压耳式耳机的婴幼儿。插入式耳机的第五个优点是可以在不更换耳机的情况下进行中耳测试和耳声发射测试；最近推出的一些诊断仪器使用这种方法。尽管插入式耳机与压耳式耳机相比更卫生，但由于放置在受试者耳道中的泡沫耳塞是一次性的，更换这些耳塞的成本对于许多机构来说是难以承受的。除了较高的费用外，插入式耳机还会对鼓膜穿孔的人产生错误的阈值，包括压力平衡管（Voss等人，2000年）。（有关穿孔的更多息，请参见图3.12。）在插入式耳机的最大输出也低于压耳式耳机在某些频率下的最大输出。由于这些差异，许多诊所保留了这两种耳机类型，并根据不同的应用情况在它们之间切换。
图3.4 Etymotic型号ER-3A插入式耳机
Circumaural earphones, a third type, have cushions that encircle the pinna. ANSI (2010) describes reference equivalent threshold SPL values (SPL values corresponding to 0 dB HL) for Sennheiser model HDA200 and Koss model HV/1A earphones. These earphones and the Etymotic ER-2 insert earphones are the only ones in the current standard that have reference values covering the extended high frequencies (8 to 20 kHz).
耳罩式耳机是第三种类型，具有环绕耳廓的垫子。 ANSI（2010）描述了Sennheiser型号HDA200和Koss型号HV / 1A耳机的参考等效阈值SPL值（对应于0dB HL的SPL值）。 这些耳机和Etymotic ER-2插入式耳机是目前标准中唯一具有覆盖扩展高频（8k至20 kHz）参考值的耳机。
Current standards for earphone calibration specify the level based on measures obtained with the earphone attached to an acoustic coupler or artificial ear. These couplers are designed to approximate the ear canal volume of an average person. Given that some clients (e.g., infants) have very small or very large ear canals (e.g., some postsurgical clients and persons with perforated eardrums), coupler measures may produce erroneous results, regardless of the earphone type (Voss et al., 2000; Voss and Herman, 2005). For these cases, measuring the SPL at the eardrum to specify the level presented to an individual patient would improve the accuracy of hearing thresholds. The probetube microphones necessary for these types of measures already exist, and hopefully, this technology will become routinely available for use in diagnostic audiometers (see Scheperle et al., 2011 for a discussion of calibration in the ear canal).
当前的耳机校准标准是根据耳机连接到声音耦合器或仿真耳上所获得的测量值来规定的。这些耦合器被设计成近似于一个普通人的耳道容积。考虑到一些受试者的耳道非常小（例如婴儿）或非常大（例如一些术后病人和耳膜穿孔的人），无论何种类型的耳机，耦合器测量都可能产生错误的结果（Voss等，2000; Voss和Herman，2005）。对于这些情况，测量鼓膜处给予个体患者的SPL将提高听力阈值的准确性。这类措施所需的探头麦克风已经存在，希望这项技术可以常规地用于诊断听力计（关于耳道校准的讨论，参见Scheperle等，2011）
Speakers
扬声器
AC thresholds can be measured using speakers as the transducer. Thresholds so obtained are known as sound-field thresholds. Sound-field thresholds are unable to provide ear-specific sensitivity estimates. In cases of unilateral hearing losses, the listener’s better ear determines threshold. This limitation and others dealing with control over stimulus level greatly limit clinical applications involving sound-field thresholds. Applications for sound-field thresholds are screening infant hearing or demonstrating to the parents their child’s hearing ability. Sound-field thresholds may also be desirable for a person wearing a hearing aid or cochlear implant.
气导阈值可以用扬声器作为换能器来测量。这样获得的阈值称为声场阈值。声场阈值无法提供特定耳的灵敏度评估。在单侧听力丧失的情况下，听者较好的耳朵决定了阈值。这种局限性和有关其他刺激程度的控制极大地限制了涉及声场阈值的临床应用。声场阈值应用于筛查婴儿听力，或向父母展示其孩子的听力能力。对于配戴助听器或人工耳蜗的人来说，声场阈值也是可取的。
In sound-field threshold measures, the orientation of the listener to the speaker has a large effect on stimulus level presented at the eardrum. A person’s head and torso as well as the external ear (e.g., pinna, ear canal, concha) affect sound levels (Shaw, 1974). Differences in SPL at the eardrum are substantial for speaker locations at different distances and different angles relative to the listener. For this reason, sound-field calibration takes into consideration these factors. A mark is usually made on the ceiling (or floor) of the room to indicate the location of the listener during testing. Even at the desired location, stimulus level at the eardrum for some frequencies can vary as much as 20 dB or more by simply having the listener move his or her head (Shaw, 1974). Calibration assumes the listener will always be facing the same direction relative to the sound source (ANSI, 2010). Furniture and other persons in the sound field also affect the stimulus level at a listener’s eardrum (Morgan et al., 1979). All of these factors add to the challenge of obtaining accurate sound-field thresholds.
在声场阈值测试中，听者相对说话者的方位对呈现在鼓膜上的刺激程度有很大影响。一个人的头部和躯干以及外耳（如耳廓、耳道、耳蜗）都会影响声音程度（Shaw, 1974）。相对于听者不同距离和不同角度的扬声器位置，鼓膜声压级的差异是显著的。因此，声场校准要考虑这些因素。通常在房间的天花板（或地板）上做一个标记，以指示测试期间听者的位置。即使在理想的位置，只要听者移动他（她）的头，一些频率在鼓膜上的刺激程度可以变化多达20分贝或更多（Shaw, 1974）。校准假定的是听者始终面对与声源相同的方向（ANSI, 2010）。声场中的设备和其他人也会影响听者鼓膜的刺激程度（Morgan et al.， 1979）。所有这些因素都增加了获得准确声场阈值的难度。
Another important consideration in sound-field threshold measures is the stimulus type. Thresholds corresponding to different frequencies are desired for plotting an audiogram, but puretones can exhibit large differences in level at different positions in a testing suite as a result of standing waves. Standing waves occur when direct sound from the speaker interacts with reflections, resulting in regions of cancellation and summation. Differences in stimulus level due to standing waves are minimized by using narrowband noise or frequency-modulated (FM) tones as the stimulus (Morgan et al., 1979). FM tones, also known as warbled tones, are tones that vary in frequency over a range that is within a few percent of the nominal frequency. This variation occurs several times per second. Under earphones, thresholds obtained with these narrowband stimuli are nearly identical to thresholds obtained with puretones, with some exceptions in persons with steeply sloping hearing loss configurations. FM tones and narrowband noise are the preferred stimuli for sound-field threshold measures.
声场阈值测量中的另一个需要考虑的重要因素是刺激类型。不同频率对应的阈值最终绘制成听力图，但是纯音由于驻波的作用，在测试套件的不同位置可以表现出较大程度的差异。当扬声器直接发出的声音与反射相互作用时，就会产生驻波，从而导致抵消和叠加。通过使用窄带噪声或调频（FM）音调作为刺激最大限度地减少了驻波引起的刺激差异（Morgan等，1979）。FM音调，又称颤音，是指频率变化范围在额定频率的百分之几以内变化的音调。这种变化每秒发生数次。在耳机下，使用这些窄带刺激获得的阈值与使用纯音获得的阈值几乎相同，但对于听力损失严重的人来说有些例外。FM音调和窄带噪声是声场阈值测量的首选刺激。
Bone Vibrators
骨振动器
A bone vibrator is a transducer that is designed to apply force to the skull when placed in contact with the head. Puretone BC thresholds are measured with a bone vibrator like the one illustrated in Figure 3.6. A separation of 15 dB or more between masked AC and BC thresholds, with BC thresholds being lower than AC thresholds, is often evidence of a conductive hearing loss. Other possible explanations for air–bone gaps and bone–air gaps are equipment miscalibration, test–retest variability, and individual differences in anatomy that cause thresholds to deviate from the groupmean data used to derive normative values for relating AC and BC thresholds.
骨振动器是一种换成器，设计用于放置在头部向颅骨施加力。纯音骨导阈值是用骨振动器测量的，如图3.6所示。掩蔽的气骨导阈值之间存在15dB或更高的分离，且骨导阈值低于气导阈值，这通常是传导性听力损失的证据。气-骨间隙和骨-气间隙的其他可能解释是设备校准错误、复测变异性和个体解剖差异，这些因素导致阈值偏离气骨导阈值标准值。
临床骨传导振动器（无线电耳型号B-72）。
For threshold measurements bone vibrators are typically placed behind the pinna on the mastoid process or on the forehead. Although forehead placement produces slightly lower intrasubject and intersubject threshold differences (Dirks, 1994), placement on the mastoid process is preferred by 92% of audiologists (Martin et al., 1998). Mastoid placement is preferred mainly because it produces between 8 and 14dB lower thresholds than forehead placement for the same power applied to the vibrator, depending on the frequency (ANSI, 2010). The median difference is 11.5 dB. Given that the maximum output limits for bone vibrators with mastoid placement are as much as 50 dB lower than that for AC thresholds, forehead placement yields an even larger difference. The inability to measure BC thresholds for higher levels means that a comparison of AC and BC thresholds is ambiguous in some cases. That is, when BC thresholds indicate no response at the limits of the equipment (e.g., 70 dB HL) and AC thresholds are poorer than the levels where no response was obtained (e.g., 100 dB HL), the audiologist cannot establish from these thresholds whether the loss is purely sensory/neural or whether it has a conductive component.
阈值测量时，骨振动器通常放置在耳廓后的乳突上或前额上。虽然前额放置会产生更小的主体内和主体间阈值差异（Dirks，1994），但92％的听力学家首选乳突位置（Martin等人，1998）。首选乳突放置是因为给振动器施加相同的力量，根据频率的不同，其测量出的阈值比前额放置低8到14 dB（ANSI，2010）。中间值为11.5 dB。考虑到乳突放置的骨振动器的最大输出限制比气导阈值低50 dB，前额放置会产生更大的差异。无法测量更高的BC阈值意味着在某些情况下气导和骨导阈值的比较是不明确的。也就是说，当骨导阈值显示在设备极限处无反应（如70dB HL），而气导阈值低于无反应处的骨导阈值（如100dB HL）时，听力学专家不能从这些阈值中确定损失仅仅是感音/神经性损失或是传导性损失。
Test Environment
测试环境
Hearing tests ideally are performed in specially constructed sound-treated chambers with very low background noise. A sound-treated room is not a sound-proof room. High-level external sounds can penetrate the walls of a sound-treated room and may interfere with test results. Because test tones near threshold can be easily masked by extraneous, external noise, test chambers have strict guidelines for maximum permissible ambient noise levels. Low background noise levels are particularly important for BC testing, when the ears remain uncovered. When testing is done in a room that meets the ANSI guidelines, the audiogram reflects that by citing ANSI S3.1 (1999), the standard governing permissible ambient noise levels. Table 3.1 shows the minimum levels of ambient noise measured in octave bands encompassing the test frequency that enable valid hearing threshold measurements at 0 dB HL.
理想的听力测试是在背景噪音非常低的特殊构造的声音处理室中进行的。声音处理室不是隔音室。高强度的外部声音可以穿透声音处理室的墙壁，并可能干扰测试结果。由于接近阈值的测试音调很容易被无关的外部噪声掩盖，因此测试室对最大允许周围环境噪声水平有严格的准则。当耳朵未遮盖时，低背景噪音水平对骨导测试尤其重要。当在符合ANSI准则的房间内进行测试时，听力图反映了标准管理所允许的周围环境噪声程度，准则引用的是ANSI S3.1（1999）。表3.1给出了在0 dB HL下有效听力阈值测量的测试频率范围内，以倍频音程测量的环境噪声的最低水平。
At times, audiologists must estimate hearing thresholds in rooms that do not meet the guidelines for minimal ambient noise. Some patients in hospital rooms or nursing homes must be tested at bedside. In those cases, test results should be clearly marked so that others know the conditions under which the test was done. When possible, these bedside tests should be performed using insert earphones, which provide a greater amount of attenuation in low frequencies where ambient noise is typically more of a problem. In these environments, BC testing, particularly in the low frequencies, may not be valid.
有时，听力师必须在不符合最低环境噪声准则的房间中评估听力阈值。一些住在病房或疗养院的病人必须在床旁接受检查。在这些情况下，应该清楚地标记测试结果，以便其他人知道测试是在什么条件下进行的。如果可能的话，这些床旁测试应该使用插入式耳机，这样在周围环境噪声是比较大的问题时，插入式耳机在低频处可以提供更大的衰减。在这些环境中，骨传导测试，尤其是在低频中，可能是无效的。
改编自美国国家标准学会。（1999年）听力测试室允许的最大周围环境噪声。ANSI S3.1-1999。纽约州纽约市：美国国家标准协会。在测量0 dB HL或更低的有效阈值时倍频音程级别不能超过列表值。
Measuring Puretone Thresholds
测量纯音阈值
Psychophysics is the field of study that relates the physical world with perception. PT thresholds are an example of a psychophysical measure relating the physical characteristics of a tone to a behavioral threshold.
心理物理学是将物理世界与感知联系起来的研究领域。纯音阈值是一种将音调的物理特征与行为阈值联系起来的心理物理测量的例子。
A psychophysical procedure describes the specific method used to obtain behavioral thresholds. The most common one used in puretone audiometry is a modified method of limits. In the method of limits, the tester has control over the stimulus. A threshold search begins with the presentation of a tone at a particular frequency and intensity that is often specified by the procedure. After each presentation of the tone (or a short sequence of pulsed tones), the tester judges whether or not the listener heard it based upon the listener’s response or lack of response. Each response determines the subsequent dB-level presentation. If a tone on a given presentation is not heard, the tone level is raised. If a tone is heard, the level is lowered. The rules of the psychophysical procedure govern the amount of the level change following each response, when to stop the threshold search, and the definition of threshold. The procedure, which is described in detail in subsequent sections, may be modified slightly based on the clinical population (e.g., the age of the listener).
心理物理程序描述了获得行为阈值的具体方法。纯音测听最常用的方法是一种改进的限制法。在限制法中，测试者可以控制刺激。阈值搜索从特定频率和强度的音调开始，该频率和强度通常由程序指定的。在每一次音调的发出之后（或者是一小段脉冲音调序列），测试人员根据听者的反应与否来判断听众是否听到了它。每个反应决定了后续的db程度。如果没有听到给定的演示音调，则提高音调强度。如果听到音调，则降低强度。心理物理程序的规则控制了每个响应之后的程度变化量、何时停止阈值搜索以及阈值的确定。该过程可能会根据临床人群（例如，听者的年龄）稍作修改，将在后续章节中详细描述。
COOPERATIVE LISTENERS AGE 5 YEARS TO ADULT (EARPHONES)
5岁至成人受试者（耳机）
Guidelines for Manual Pure Tone Audiometry is a publication that describes a uniform method for measuring thresholds (American Speech-Language-Hearing Association [ASHA], 2005). The goal of the guideline is to minimize differences across clinics by standardizing procedures. The committee that drafted this consensus document understood that its recommendations represent general guidelines and that clinical populations may require variations of the procedure.
“人工纯音测听指南”是一份介绍测量听阈的统一方法的出版物（美国语言听力协会[ASHA]，2005年）。该指导方针的目标是通过标准化程序最大限度减少不同诊所间的差异。起草这份共识文件的委员会理解，其建议代表一般准则，临床人群可能工作时需要改变程序。
Instructions
说明
Puretone audiometry begins with instructing the individual being tested. The instructions are a critical part of the puretone test, because thresholds measured using this clinical procedure are biased by the willingness of a person to respond. Some listeners wait for a tone to be distinct before they respond, which leads to higher thresholds than for someone who responds whenever they hear any sound that could be the tone. This bias is controlled in the instructions by informing listeners to respond any time they hear the tone no matter how faint it may be. A study by Marshall and Jesteadt (1986) shows that response bias controlled for in this manner plays only a small role (a few dB at most) in PT thresholds obtained using the ASHA guideline. Marshall and Jesteadt (1986) also reported that the response bias of elderly listeners was not different than that of a group of younger persons. Before the study by these authors, it was believed that elderly persons might adopt an extremely conservative response criterion, resulting in artificially elevated thresholds compared to those of younger persons.
纯音测听是从指导被测试者开始。“指导”是纯音测试的一个关键部分，因为使用这一临床程序测量的阈值会因一个人的反应意愿而产生偏差。有些听者会等待清晰的音调才会做出反应，这会导致其反应阈值都要高于那些在听到任何可能是音调的声音都作出反应的人的阈值。这种偏差可以在指导中控制，只要听到音调，无论多么微弱，都要作出反应。Marshall和Jestet（1986）的一项研究表明，以这种方式控制的反应偏差在使用ASHA准则做出的纯音阈值中只起到很小的作用（最多几dB）。Marshall和Jestet（1986）报告还提到，老年人的反应偏差与一组年轻人的反应偏差没什么不同。在这些作者的研究之前，人们认为老年人可能会采用一个非常保守的反应标准，与年轻人相比，这会导致阈值明显升高。
According to the ASHA (2005) guideline, the instructions should also include the response task (e.g., raise your hand or finger, or press a button), the need to respond when the tone begins and to stop responding when it ends, and that the two ears are tested separately. Although not in the ASHA guideline, instructions asking the examinee to indicate which ear the sound is heard in may be useful. This is especially important in cases of unilateral or asymmetrical hearing losses where cross-hearing is possible.
根据ASHA（2005）的指南，指导还应该包括响应任务（例如，举起你的手或手指，或按下一个按钮），当音调开始时作出响应和结束时停止响应，以及两个耳朵分别测试。虽然ASHA指南中没有记录，但是“指导”要求被试者指出在哪个耳朵里听到声音可能是有帮助的。这在可能发生交叉听力的单侧或非对称听力损失的情况下尤为重要。
The examiner should present the instructions prior to placement of earphones. Earphones attenuate external sounds making speech understanding more difficult, particularly for persons with hearing loss. Listeners should also be queried after the instructions are presented to determine if they understood what was said. Sample instructions are given below:
检查者应在放置耳机前说明。带上耳机会使外界声音变弱，使语音理解更加困难，尤其对于有听力损失的人。在给出“指导”之后，还应该询问听者，以确定他们是否理解所讲的内容。示例说明如下：
You are going to hear a series of beeps, first, in one ear and then in the other ear. Respond to the beeps by pressing the button [switch] when one comes on and release it as soon as it goes off. Some of the beeps will be very faint, so listen carefully and respond each time you hear one. Do you have any questions?
你会听到一系列的哔哔声，先是一只耳朵，然后另一只耳朵。当听到哔哔声时，按下【开关】按钮，声音消失时立即松开。有些哔哔声会非常微弱，所以要仔细听，每次听到哔哔声都要做出反应。你有什么问题吗？
Earphone Placement
耳机放置
The earphones should be placed by the examiner. For convenience, earphones are color coded; red and blue correspond to the right and left ears, respectively. Prior to placement of earphones, clients are asked to remove jewelry such as earrings and glasses if they will interfere with the placement of the earphone. This is particularly relevant for supra-aural earphones.
耳机应由检查者放置。为方便起见，耳机采用彩色编码；红色和蓝色依次对应右耳和左耳。在放置耳机之前，如果诸如耳环和眼镜之类首饰干扰耳机的放置，则要求受试者摘除。 这对于压耳式耳机尤为重要。
For circumaural and supra-aural earphones, the diaphragm of the earphone should be centered over the ear canal. The examiner should view each ear while the phone is being placed. Immediately after placement, the headband is tightened enough to make the earphone perpendicular to the floor when the examinee is sitting upright.
对于耳罩式耳机和压耳式耳机，耳机的振膜应位于耳道的中心位置。在放置耳机时，检查者应查看每只耳朵。放置完毕后，立即收紧头带，以便当考生直坐时，耳机垂直于地面。
The first step in placement of insert earphones is to attach a spring-loaded clip that holds the transducer in place to the examinee’s clothing. The clip can be attached to clothing near the shoulder (or behind a child’s neck) to keep the plug from being pulled out of the ear. In some newer implementations that combine middle-ear and otoacoustic emission measurements, the earphone is attached to a headband. For both types of support, the audiologist compresses the foam plug and inserts it into the ear canal so that its outer edge lines up with the tragus.
插入式耳机放置的第一步是将附有弹簧夹的换能器固定在检查者的衣服上。这种夹子可以固定在靠近肩膀（或孩子脖子后面）的衣服上，防止耳塞从耳朵里拉出来。在一些结合中耳测量和耳声发射测量的较新型装置中，耳机附在头带上。对于这两种类型的设备，听力师压缩泡沫塞并将其插入耳道，使其外缘与耳屏对齐。
Placement of the Bone-conduction Vibrator
骨传导振动器的放置
Although some recommend forehead placement (Dirks, 1994), typically audiologists place the BC oscillator on the most prominent part of the mastoid process. While holding the oscillator against the mastoid process with one hand, the headband is fit over the head to hold the oscillator in place using the other hand. The oscillator surface should be set directly against the skin, not touching the pinna, and with no hair or as little hair as possible between the oscillator and the skin. Some audiologists play a continuous lowfrequency tone while moving the oscillator slightly side to side, asking the listener to report the location at which the tone is the strongest.
尽管有人建议前额放置（Dirks，1994），但通常听力师将骨传导振动器置于乳突最突出的部位。用一只手将振荡器固定在乳突上，头带戴在头上，另一只手将振动器固定在适当的位置。振动器表面应直接贴在皮肤上，不要接触耳廓，并且在振荡器和皮肤之间不要有毛发或尽可能少的毛发。一些听力专家在轻轻左右移动振荡器的同时播放连续的低频音调，要求听者报告音调最强的位置。
Audiometric Procedure for Threshold Measurement
听阈测量程序
The ASHA Guideline (2005) recommends starting a threshold search from either well below threshold or using a suprathreshold tone that familiarizes the participant with the stimulus. Most clinicians prefer the familiarization method. For the familiarization approach, testing usually begins at 1,000 Hz at 30 dB HL unless prior knowledge of the examinee’s hearing suggests otherwise (ASHA, 2005). At 1,000 Hz, an examinee is more likely to have residual hearing than at a higher frequency, and test–retest reliability is excellent. Testing begins with an examinee’s self-reported better ear. If the examinee believes both ears are identical, testing begins by convention with the right ear. The better ear is tested first to provide a reference to know whether masking needs to be delivered to obtain a valid estimate of threshold for the poorer ear.
ASHA指南（2005）建议从低的阈值或使用听者熟悉刺激的阈上音调开始阈值搜索。大多数临床医生更喜欢“熟悉性”的方法。对于“熟悉性”方法，除非事先了解受试者的听力，否则测试通常从1000 Hz，30 dB HL开始（ASHA，2005）。受试者在1,000 Hz比更高频率更容易出现残余听力，并且复测可靠性好。测试从受试者自我感觉听力更好的耳朵开始。如果受检者认为双耳听力是相同的，则按照惯例从右耳开始测试。首先对较好的耳朵进行测试，以提供一个参考，了解是否需要提供掩蔽以获得对差耳阈值的有效评估。
Tonal duration is an important factor in a puretone test. On most audiometers, the option exists to select either pulsed or manual presentation. A 1- to 2-second duration tone is recommended for manual presentation (ASHA, 2005). The duration is determined by the amount of time the interrupter switch is held down. Pulsed tones are achieved by selecting this option on the audiometer’s front panel. If pulsed tones are selected, then the audiometer alternately presents the tone followed by a short silent interval (typically 225 ms on followed by 225 ms off) for as long as the interrupter switch is depressed. The minimum duration for a single pulse of the tone is critical. Numerous psychoacoustic studies have shown that tonal durations between roughly 200 ms and 1 second or more yield nearly identical thresholds (Watson and Gengel, 1969). By contrast, the same studies show that durations less than 200 ms result in higher thresholds. For this reason, audiometers are designed to have a nominal pulse duration of 225 ms (ANSI, 2010). Pulsed and manually presented tones presented from audiometers that maintain tonal durations between 200 ms and 2 seconds yield nearly identical thresholds, as the psychoacoustic studies suggest. However, pulsed tones are preferred for two reasons. Most patients prefer pulsed tones (Burk and Wiley, 2004), and pulsed tones also reduce the number of presentations required to find threshold in persons with cochlear hearing loss who have tinnitus (Mineau and Schlauch, 1997). Apparently, pulsed tones help patients to distinguish the puretone signal from the continuous or slowly fluctuating noises generated from within their auditory system (tinnitus), thereby reducing false-positive responses. False-positive responses can lengthen test time (Mineau and Schlauch, 1997), which is costly to an audiology practice.
音调持续时间是纯音测试中的一个重要因素。在大多数听力计上，可以选择脉冲或手动演示。1到2秒的持续音调被建议于手动演示时使用（ASHA，2005）。持续时间由中断开关按下的时间长短确定。脉冲音调是通过在听力计的前面板上选择此选项来实现的。如果选择脉冲音调，则只要按下中断开关，听力计就会交替呈现音调和一个短的无声间隔。（通常为225毫秒打开，然后225毫秒关闭）。音调的单一脉冲的最短持续时间至关重要。大量的心理声学研究表明，大约200毫秒到1秒或更长时间的音调持续时间产生几乎相同的阈值(Watson和Gengel，1969)。相反，同样的研究表明，小于200ms的持续时间会导致更高的阈值。因此，听力计的额定脉冲持续时间为225毫秒（ANSI，2010年）。心理声学研究表明，由听力计呈现的脉冲和手动呈现的音调在200毫秒到2秒之间产生几乎相同的阈值。然而，首选脉冲音有两个原因。大多数患者更喜欢脉冲音调（Burk和Wiley，2004年），脉冲音调也减少了患有耳鸣的耳蜗性听力损失患者找到阈值所需的呈现次数（Mineau和Schlauch，1997年）。显然，脉冲音调可以帮助患者区分纯音信号和听觉系统（耳鸣）中产生的持续或缓慢的噪声，从而减少假阳性反应。假阳性反应会延长测试时间(Mineau和Schlauch，1997)，这对听力学实践来说代价很高。
Thresholds typically are obtained using a modified Hughson–Westlake down-up procedure, which is a specific implementation of a method-of-limits procedure (Carhart and Jerger, 1959; Hughson and Westlake, 1944). The examiner begins the threshold-finding procedure by presenting a tone at 30 dB HL (ASHA, 2005). If the listener responds, the level of the tone is decreased in 10-dB steps until the listener no longer responds. If the listener does not respond to this initial 30-dB tone, the examiner raises the tone in 20-dB steps until a response is obtained. After every response to a tone, the level of the tone is decreased in 10-dB steps until there is no response. For subsequent presentations when there is no response, the examiner raises the level of the tone in 5-dB steps until a response is obtained. Following this “down-10/up-5” rule, the tester continues until the threshold is bracketed a few times, and a threshold estimate is obtained. ASHA (2005) recommends that threshold should correspond to the level at which responses were obtained for two ascending runs, which is what most clinicians based their thresholds on even when the ASHA (1978) Guideline recommended that thresholds be based on three ascending runs. Research based on computer simulations of clinical procedures (Marshall and Hanna, 1989) supports the clinician’s position and that of the ASHA (2005) guideline. The computer simulations of thresholds based on three ascending runs showed only a minimal reduction of the variability when compared to thresholds based on two ascending runs. Listeners who produce inconsistent responses are an exception, and for these listeners, additional measurements can be made to confirm the threshold estimate.
阈值通常是使用修改后的HW升降法获得的，该过程是限制法的具体实现（Carhart and Jerger，1959；Hughson and Westlake，1944）。测试者通过30dBHL的音调开始阈值测试过程（Asha，2005年）。如果受试者响应，则音调以每次10dB降低，直到受试者不再响应。如果听者对最初的30分贝音调没有反应，则检查者以每次20dB提升音调，直到出现响应。在对音调的每次响应之后，音调以每次10dB降低，直到没有响应。对于没有响应的情况下，检查者以每次5dB提升音调，直到获得响应。在该“降10 /升5”规则之后，测试继续，直到阈值被大致测到几次，并获得阈值评估值。ASHA（2005）建议阈值应该对应于两次上升时的响应的水平，这是大多数临床医生基于的阈值，即使ASHA（1978）指南建议阈值基于三次上升时的响应的水平。基于计算机模拟临床程序的研究（Marshall和Hanna，1989）支持临床医生的立场和ASHA（2005）指南的立场。基于三次上升运行的阈值的计算机模拟显示，与基于两次上升运行的阈值相比，只有很小的降低。产生不一致响应的受试者是一个例外，对于这些受试者，可以进行额外的测量以确定阈值评估值。
After a threshold is measured at 1,000 Hz, the next frequencies that are examined depend on the goal, but the higher frequencies are typically tested prior to the lower frequencies. For diagnostic audiometry, thresholds are measured at octave intervals between 250 and 8,000 Hz, along with 3,000 and 6,000 Hz. Intra-octave thresholds between 500 and 2,000 Hz should be measured when thresholds differ by 20 dB or more between two adjacent octaves. ASHA (2005) also recommends that 1,000 Hz be tested twice as a reliability check. Refer to the ASHA (2005) guidelines for specifics about the recommended protocol and Chapter 6 for details about the use of masking noise to eliminate the participation of the nontest ear. Masking noise is needed whenever the threshold difference between ears is equal to or exceeds the lowest possible values for interaural attenuation. For BC testing, masking is needed to verify results anytime an air–bone gap in the test ear of greater than 10 dB is observed. For AC testing, masking is needed when the difference between the AC threshold in the test ear and the BC threshold of the nontest ear is greater than or equal to 40 dB for supra-aural earphones, and considerably more for insert earphones, especially in the low frequencies (Killion and Villchur, 1989). Specific recommendations for insert earphones cannot be made until a study with a larger sample size is completed.
在以1,000Hz测量阈值之后，下一个被检查的频率取决于所需目标，但是通常较高频率在较低频率之前测试。对于诊断听力测量，阈值测量的倍频音程在250至8，000赫兹之间，以及3，000和6，000赫兹。当两个相邻倍频音程之间的阈值相差20 dB或更多时，应测量500到2,000 Hz之间的半倍频程阈值。ASHA（2005）还建议将1000hz测试两次作为可靠性检查。有关使用掩蔽噪声消除非测试耳朵参与的详细信息，请参阅ASHA（2005）指南中的具体推荐方案和第6章的内容。只要两耳之间的阈值差等于或超过耳间衰减的最低可能值时，就需要施加掩蔽噪声。对于骨导测试，只要观察到测试耳中的气骨间隙大于10 dB，就需要进行掩蔽以验证结果。在气导测试中，使用压耳式耳机时，当测试耳的气导阈值与非测试耳的骨导阈值之间的差异大于或等于40dB时，需要掩蔽，对于插入式耳机，尤其是在低频时，掩蔽值要大的多（Killion和Villchur，1989）。在完成较大样本量研究之前，不能对插入式耳机做出具体建议。
TESTING CHILDREN YOUNGER THAN AGE 5 YEARS AND PERSONS WITH SPECIAL NEEDS
测试对5岁以下儿童及有特殊需要的人员
For most children younger than age 5 years, audiologists have special procedures that they employ to measure PT thresholds. Some of these same procedures are also appropriate for persons older than 5 years who have cognitive deficits. Chapter 24 on pediatric hearing assessment describes these procedures and their interpretation.
对于大多数5岁以下的儿童，听力学家采用特殊方法来测量纯音阈值。其中一些同样的方法也适用于5岁以上有认知缺陷的人。第24章描述了关于儿科听力评估程序及其解读。
Audiometric Interpretation
听力测定解读
PT thresholds are displayed in tabular or graphical formats. The tabular format is useful for recording the results of serial monitoring of thresholds, as in a hearing conservation program, but in many applications, thresholds are plotted on an audiogram. ASHA (1990), in a publication entitled Guidelines for Audiometric Symbols, suggests a standardized form for the audiogram. Although other formats for plotting audiograms are acceptable, it is helpful to use a standardized format for ease of interpretation across clinics. The audiogram consistent with that recommended in the ASHA guidelines (1990) is shown in Figure 3.7 along with recommended symbols. This audiogram only covers the conventional frequencies. Thresholds for extended high frequencies are plotted often in units of dB SPL, because average extended high-frequency thresholds vary over a wide range with the age of the listener, making dB SPL a better reference than dB HL for comparing thresholds to norms for listeners of different ages. Conversion between units of dB SPL and dB HL can be accomplished for three different earphone models by consulting reference levels published in ANSI (2010).
纯音阈值以表格或图形格式显示。表格格式对于记录连续监测阈值的结果很有用，就像在听力保护程序中一样，但在许多应用中，阈值被绘制在听力图上。ASHA（1990）在题为“听力符号指南”的出版物中提出了听力图的标准化格式。尽管使用其他格式绘制听力图也是可以接受的，但使用标准化格式以助于临床之间的解释。如图3.7展示了符合ASHA指南（1990）建议的听力图，并附有推荐符号。该听力图只包含常规频率。扩展高频的阈值通常以dB SPL为单位绘制，因为扩展高频的平均阈值随着受试者的年龄在变化范围很大，使得dB SPL比dB HL更适合于比较不同年龄的听者的常规阈值。通过参考ANSI（2010）中公布的参考数据，可以针对三种不同的耳机型号实现dB SPL和dB HL之间的转换。
推荐的听力图和符号（Asha，1990），伴有感觉/神经听力损失。re和le分别代表右耳和左耳。“Response”一词缩写为“resp”。
Audiograms are often classified by categories based on the degree of hearing loss. A number of authors have published systems for classifying hearing loss based on the average AC thresholds for three frequencies. The frequencies used for this purpose are usually 500, 1,000, and 2,000 Hz, often referred to as the three-frequency puretone average (PTA). Table 3.2 shows the categories for the degree of loss based on this PTA for three different authors (Goodman, 1965; Jerger and Jerger, 1980; Northern and Downs, 2002). The first category is normal hearing. Note that none of the three authors agree on the upper limit for normal, which ranges from 15 to 25 dB HL. Northern and Downs (2002) suggest using 15 dB HL as the upper limit for normal hearing for the three-frequency PTA for children between 2 and 18 years of age and a higher limit for adults. A 15 dB HL upper limit for normal hearing may produce a significant number of false positives when applied to thresholds for individual audiometric frequencies, even in children (Schlauch and Carney, 2012). Regardless of the value used as an upper limit for normal hearing, keep in mind that an ear-related medical problem can still exist even though all thresholds fall within the defined normal range. For example, the presence of a significant air–bone gap might indicate the presence of middle-ear pathology even though all AC thresholds fall within normal limits.
听力图通常根据听力损失程度按类别分类。许多作者已经公布了基于三个频率的平均气导阈值对听力损失进行分类的系统。用到的频率通常为500,1,000和2,000Hz，通常称为三频纯音平均值（PTA）。表3.2给出了三个不同作者基于PTA的损失程度分类（Goodman，1965; Jerger和Jerger，1980; Northern和Downs，2002）。第一类是正常听力。请注意，三位作者均未就正常上限达成一致，范围为15至25 dB HL。 Northern和Downs（2002）建议使用15 dB HL作为2至18岁儿童的三频纯音平均值（PTA）的正常听力上限，成人使用较高上限。当应用于个别测听频率的阈值时，正常听力的上限15dbHL可能会产生大量的假阳性，即使在儿童中也是如此（Schlauch和Carney，2012）。不管用什么值作为正常听力的上限，请记住，即使所有阈值都在规定的正常范围内，与耳朵有关的医学问题仍然可能存在。例如，即使所有气导阈值都在正常范围内，但显著的气骨间隙可能表明存在中耳病变。
虽然所引用的三个参考文献在作为严重损失的接受值上有所不同，但90dB HL或更大的损失被广泛认为是听力和耳聋之间的定性和定量界限。
The original intent of classification system for severity of loss based on a three-frequency PTA was to express, in a general way, the degree of handicap associated with the magnitude of the loss. These categories are only somewhat successful at achieving this goal, because (1) handicap is dependent on many factors related to an individual’s needs and abilities, (2) only some of the speech frequencies are assessed using this three-frequency average (speech frequencies range from 125 to 6,000 Hz), and (3) identical amounts of hearing loss sometimes result in large differences in the ability to understand speech and, as a consequence, the degree of disability associated with the loss. Despite these limitations, many audiologists use these categories routinely to summarize the amount of loss in different frequency regions of an audiogram when describing results to other professionals or to a client during counseling.
基于三频PTA的损失严重程度分级系统的最初目的是以一般方式表示与损失程度相关的障碍程度。这些类别只在一定程度上成功地实现了这一目标，因为（1）障碍取决于与个人需求和能力相关的许多因素，（2）只有部分语音频率是用这三个频率的平均值进行评估（语音频率在125至6，000 Hz之间），（3）相同数量的听力损失有时会导致理解语言能力的巨大差异，从而导致与听力损失相关的残疾程度。尽管有这些限制，但许多听力学家在向其他专业人员或咨询期间的客户描述结果时，经常使用这些类别来总结听力图不同频率区域的损失量。
Another factor in audiometric classification is the type of hearing loss. The type of hearing loss is determined by comparing the amount of hearing loss for AC and BC thresholds at the same frequency. A sensory/neural hearing loss has an equal amount of loss for AC and BC thresholds (as shown in Figure 3.7). By contrast, a conductive loss has lower BC thresholds than AC thresholds (as shown in Figure 3.8). Conductive-loss magnitude is described by the decibel difference between AC and BC thresholds. This difference is known as the air–bone gap, a value that has a maximum of about 65 dB† (Rosowski and Relkin, 2001). Due to test–retest differences, an air–bone gap needs to exceed 10 dB before it is considered significant. A mixed hearing loss shows a conductive component and a sensory/neural component. In other words, a mixed loss has an air–bone Classification gap, and the thresholds for BC fall outside the range of normal hearing (Figure 3.9).
听力损失分级的另一个因素是听力损失的类型。通过比较相同频率下气导和骨导阈值的听力损失量来确定听力损失的类型。感音/神经性听力损失中气导和骨导阈值具有相等的损失量（如图3.7所示）。相比之下，传导性听力损失中骨导阈值损失低于气导阈值（如图3.8所示）。传导损耗幅度是通过气导和骨导阈值之间的分贝差来描述。这种差异被称为气骨间隙，最大值约为65 dB（Rosowski和Relkin，2001）。由于复测的差异，气骨间隙需要超过10 dB才被认为是显著的。混合性听力损失包含传导性成分和感觉/神经性成分。换句话说，混合损失具有气骨间隙，并且骨导的阈值在正常听力范围之外（图3.9）。
图3.8 双侧传导性听力损失。这些标绘值代表Fria等人（1985）在一组中耳炎儿童报告中的平均损失。
图3.9 混合型听力损失
Yet another way that audiograms are described is by the hearing-loss configuration. The configuration takes into account the shape of the hearing loss. A description of the configuration of the loss helps in summarizing the loss to patients and to other professionals and often provides insight into the etiology or cause of the loss. Some typical shapes and the criteria used to describe them are shown in Table 3.3.
描述听力图的另一种方式是听力损失结构。该结构考虑了听力损失的形状。对损失结构的描述有助于对患者和其他专业人员的不足进行总结，并常常有助于了解损失的病因或原因。表3.3显示了一些典型的形状和用于描述它们的标准。
据Carhart R.(1945) 改编，一种改进的听力图分类方法。《喉镜》5,1 - 15和Lloyd LL, Kaplan H.(1978)《听力判读:基础听力手册》。马里兰州巴尔的摩市:大学公园出版社。
An audiogram is summarized verbally by the degree, type, and configuration of the hearing loss for both ears. If a person has normal thresholds in one ear and a hearing loss in the other ear, this is known as a unilateral hearing loss. A loss in both ears is described as a bilateral hearing loss. Bilateral losses are described as symmetric (nearly equal thresholds in both ears) or asymmetric.
听力图是根据双耳听力损失的程度、类型和结构口头总结出来的。如果一个人的一只耳朵有正常的阈值，另一只耳朵有听力损失，这就是所谓的单侧听力损失。双耳的损失称为双侧听力损失。双侧损失分为对称（双耳阈值几乎相等）或不对称。
Some Limitations of Puretone Testing
纯音测试的一些局限性
TEST–RETEST RELIABILITY
复测可靠性
PT thresholds are not entirely precise. Consider a cooperative adult whose AC thresholds are measured twice at octave intervals between 250 and 8,000 Hz. For these two measures, assume too that the earphones are removed and replaced between tests. For this situation, the probability of obtaining identical thresholds at each frequency is small. This is due to test–retest variability. Test–retest variability is also responsible for BC thresholds not always lining up with AC thresholds in persons with pure sensory/neural losses. As reported by Studebaker (1967), test–retest variability causes false air–bone gaps and false bone–air gaps (BC thresholds poorer than AC thresholds). The source of this variability is a combination of variations in the person’s decision process, physiologic or bodily noise, a shift in the response criterion, and differences in transducer placement. It is assumed that the equipment is calibrated correctly for successive tests and that the standard is not in error (Margolis et al., 2013).
纯音阈值并不完全准确。考虑一个成人合作者，其气导阈值在250到8,000 Hz之间的倍频音程将测量两次。对于这两次措施，假设耳机在测试之间被移除和更换。对于这种情况，在每个频率上获得相同阈值的概率很小。这是由于复测的变异性。复测变异性也是导致单纯感音/神经性损伤患者的骨导阈值与气导阈值不总是一致的原因。正如Studebaker（1967）报道的那样，复测的变异性导致假的气骨间隙和假的骨气间隙（骨导阈值比气导阈值差）。这种变异性的来源是人的决策过程中的变化、生理或身体噪声、反应标准的变化和换能器位置的差异的组合。假设设备已针对连续试验进行了正确校准，并且标准无误(Margolis et al., 2013)。
The inherent variability of PT thresholds poses a problem for audiologists who are faced with making clinical decisions based on these responses. Audiologists frequently need to assess whether hearing has changed significantly since the last test, whether hearing is significantly better in one ear than the other, and whether an air–bone gap is significant.
纯音阈值的固有变异性给听力学家提出了一个问题，他们要根据这些反应做出临床决策。听力学家经常需要评估自上次测试以来，听力是否发生了显著的变化，一只耳朵的听力是否明显好于另一只耳朵，以及气骨间隙是否显著。
A good place to begin with understanding test–retest variability is to consider the standard deviation (SD) of test–retest differences at a single frequency. When a 5-dB SD is assumed, threshold differences on retest of 15 dB or more are rarely expected if only a single threshold measurement is retested. By contrast, when complete audiograms are assessed, the likelihood of obtaining a large threshold difference at one frequency on retest increases. For example, 15 dB or greater differences on retest are expected only 1.24% of the time when the threshold for a single frequency is assessed. When thresholds for six frequencies are assessed in each ear (octave intervals between 0.25 and 8 kHz), 14% of the persons tested would be expected to have at least one threshold differing by 15 dB or more (Schlauch and Carney, 2007). Thus, differences of 15 dB or more in these applications would be much more commonplace than those predicted by the SD of inter-test differences for a single frequency.
理解复测变异性的一个好的起点是考虑在单个频率下测试重测差异的标准偏差（SD）。当假设5dB SD时，如果只对单个阈值测量进行了重新测试，则重新测试时的阈值差异很少达到15 db或更大。相比之下，当对整个听力图进行评估时，重新测试时在一个频率上获得较大阈值差的可能性增加。例如，当评估单个频率的阈值时，预计出现5dB或更大重测差异仅为1.24%。当在每个耳朵中评估6个频率的阈值（0.25到8千赫之间的倍频音程）时，14%的被测试者预计至少有一个阈值相差15分贝或更多（Schlauch和Carney，2007年）。因此，在这些情景中15dB或更大的差异将比单个频率测试间的标准差预测的差异更为常见。
Several methods have been proposed to assess the significance of threshold differences on retest for complete audiograms (Schlauch and Carney, 2007). These methods usually require that thresholds for more than one frequency contribute to the decision process, although some accept a large change for a single frequency, such as 20 dB or more, as a significant difference. One of these methods defines a significant threshold shift by a minimal change in a PTA. For instance, the Occupational Safety and Health Administration (1983) defines a notable threshold shift (in their terminology, a standard threshold shift) as a 10-dB or greater change in the PTA based on thresholds for 2, 3, and 4 kHz in either ear. These frequencies were selected because they include those that are susceptible to damage by occupational noise and have stable test–retest reliability. A second commonly used approach requires threshold differences to occur at adjacent frequencies. One rule that is applicable to many situations defines a significant threshold shift as one for which two adjacent thresholds differ by 10 dB or more on retest. This criterion has been applied widely in audiometric studies and is sometimes combined with other criteria to arrive at a decision (ASHA, 1994). A third approach recommends repeating threshold measurements during a single session to improve audiometric reliability (National Institute for Occupational Safety and Health, 1998). This method is paired with a rule or rules defining the criterion for a significant threshold shift. The notable difference between this method and the others described earlier is that the criterion defining a threshold shift must be repeatable to be accepted as significant.
有几种方法被提出用来评估整个听力图重测中阈值差异的显著性（Schlauch和Carney，2007）。这些方法通常要求多个频率的阈值参与决策过程，尽管有些方法接受单个频率（如20 dB或更多）的较大变化作为显著差异。其中一种方法通过PTA中的最小变化来确定显著的阈值偏移。例如，职业安全和健康管理局（1983年）根据任一耳中2、3和4 kHz的阈值改变10 dB或更大的PTA变化，确定了一个显著的阈值偏移（在其术语中，标准阈值偏移）。选择这些频率是因为它们包括那些易受职业噪声损害并具有稳定的复测信度的频率。第二种常用的方法要求在相邻频率处出现阈值差异。一个适用于许多情况的规则是将标记阈值偏移定义为两个相邻阈值在重测时相差10dB或更多。这一标准在听力学研究中得到了广泛的应用，有时还与其他标准相结合以做出决定（ASHA，1994）。第三种方法建议在单个会话期间重复阈值测量以提高听力测量的可靠性（National Institute for Occupational Safety and Health，1998）。该方法与一个或多个规则结合，这些规则定义了显著阈值偏移的标准。此方法与前面描述的其他方法之间的显着差异在于，定义阈值偏移的标准必须是可重复的，才能被认为显著的。
The examples in this section on the variability of PT thresholds have assumed a fixed SD of test–retest differences of ±5 dB for all audiometric frequencies. Although 5 dB is a reasonable average value for many situations, studies show that the SD varies with type of earphone, the time between tests, and even with audiometric frequency (Schlauch and Carney, 2007)
本节中有关纯音阈值变异性的示例假设了一个固定的标准差，即所有测听频率的重测差异为±5dB。虽然在许多情况下，5dB是一个合理的平均值，但研究表明，标准偏差（sd）会随耳机类型、测试间隔时间、甚至听力测量频率而变化。
VIBROTACTILE THRESHOLDS
振动触觉阈值
In persons with significant hearing losses, sound vibrations produced by earphones and bone vibrators may be perceived through the sense of touch. Such thresholds are known as vibrotactile thresholds.
对于严重听力受损的人来说，耳机和骨振动器产生的声音振动可通过触觉感知。这种阈值称为振动触觉阈值。
Figure 3.10 illustrates the range of levels found to yield vibrotactile thresholds for a supra-aural earphone and a bone vibrator. A threshold occurring within the range of possible vibrotactile thresholds is ambiguous; it could be a hearing threshold or a vibrotactile threshold. Because relatively low vibrotactile thresholds are observed for BC at 250 and 500 Hz, a false air–bone gap is likely to occur in persons with significant sensory/neural losses at these frequencies.
图3.10说明了为压耳式耳机和骨振动器产生振动触觉阈值的水平范围。在可能的振动阈值范围内出现的阈值是不明确的；可以是听力阈值或振动触觉阈值。由于在250和500 Hz下观察到的骨导振动触觉阈值相对较低，因此在这些频率下，感音/神经性损失较大的人很可能出现假的气-骨间隙。
骨传导（虚线）和气导（实线）的平均振动触觉阈值。响应范围由阴影区域指示。改编自Boothroyd和Coulwell（1970年）
Boothroyd and Cawkwell (1970) recommend asking the client if they “feel” the stimulus or “hear” the stimulus as a means to differentiate between these two outcomes. Persons with experience with auditory sensations can usually make this distinction.
Boothroyd和Cawkwell（1970）建议询问患者是“感觉到”刺激还是“听到”刺激，以此作为区分这两种结果的一种方法。有听觉感受经验的人通常可以做出这种区分。
The values for vibrotactile thresholds illustrated in Figure 3.10 are based on only nine listeners. A more detailed study needs to be conducted to specify these ranges more precisely for the transducers in current use.
图3.10所示的振动触觉阈值仅基于9个受试者。需要进行更详细的研究，以便更准确地为当前使用的换能器指定这些范围。
BONE-CONDUCTION THRESHOLDS: NOT A PURE ESTIMATE OF SENSORY/NEURAL RESERVE
骨传导阈值：感觉/神经的性损伤的非纯粹评估
The goal of BC testing is to obtain an estimate of sensory/ neural reserve, but BC thresholds sometimes are influenced by the physiologic properties of the external, middle, and inner ears. The BC vibrator sets the skull into vibration, which stimulates the cochlea, but this does not happen in isolation. When the skull is vibrated, the middle-ear ossicles are also set into motion, and this inertial response of the ossicular chain contributes to BC thresholds. Changes in the external and middle ear can modify the contribution of the inertial response, which may result in significant changes in BC thresholds (Dirks, 1994).
骨导测试的目的是获得感音/神经性听力损失的估值，但是骨导阈值有时会受到外、中、内耳生理特性的影响。骨导振动器使颅骨振动，从而刺激耳蜗，但这不是孤立发生的。当颅骨振动时，中耳听小骨也开始运动，听骨链的惯性响应有助于骨导阈值。外耳和中耳的变化可以改变惯性响应，这可能导致骨导阈值的显著变化（Dirks, 1994）。
A classic example of a middle-ear problem that influences BC thresholds is otosclerosis. Otosclerosis frequently causes the footplate of the stapes to become ankylosed or fixed in the oval window. This disease process and some other types of conductive losses (e.g., glue ear) (Kumar et al., 2003) reduce the normal inertial response of the ossicles to BC hearing. The result is poorer thresholds that form a depressed region of BC hearing known as Carhart’s notch (Carhart, 1950). This notch, which typically shows poorer BC thresholds between 500 and 4,000 Hz with a maximum usually at 2,000 Hz of 15 dB, disappears following successful middle-ear surgery. The finding that BC thresholds improve following middle-ear surgery is strong evidence that these poorer BC thresholds observed in stapes immobilization are due to a middle-ear phenomenon rather than a change in the integrity of the cochlea.
中耳问题影响骨导阈值的一个典型例子是耳硬化症。耳硬化症通常导致镫骨的足板变得僵硬或固定在卵形窗。该疾病和一些其他类型的传导性损失（例如，胶耳）（Kumar等人，2003）降低了听小骨对骨导听力的正常惯性响应。结果是较差的阈值形成了一个骨导听力的下降区域，被称为“卡哈切记”（Carhart，1950）。此切迹通常在500-4000 Hz之间出现较差的骨导阈值，最大值通常在2000 Hz，15dB，在成功施行中耳手术后消失。中耳手术后发现骨导阈值改善表明，在镫骨固定中观察到的这些较差的骨导阈值是由于中耳现象而不是耳蜗完整性的改变。
A frequently observed example of middle-ear problems affecting BC thresholds occurs in persons with otitis media with effusion. In this group, falsely enhanced BC thresholds in the low frequencies (1,000 Hz and below) are seen often. The magnitude of the enhancement can be as much as 25 dB (Snyder, 1989). Upon resolution of the middle-ear problem, these previously enhanced BC thresholds become poorer and return to their premorbid values.
中耳问题影响骨导阈值的一个常见例子发生在分泌性中耳炎患者身上。这一组中，在低频（1，000 Hz及以下）中经常看到虚假增强的骨导阈值。增强的幅度可达25dB（Snyder，1989）。在中耳问题解决后，这些先前增强的骨导阈值变得更差，并恢复到其发病前的值。
Similarly, enhancement in BC thresholds occurs for low frequencies with occlusion of the external ear canal by a supra-aural ear phone. This low-frequency BC enhancement, known as the occlusion effect, must be considered when occluding the nontest ear to present masking noise during BC testing. However, when the masking noise is presented using an insert earphone with the foam plug inserted deeply into the ear canal, the amount of the lowfrequency enhancement is smaller than it is when supraaural earphones are used to deliver the masking noise (Dean and Martin, 2000). Further, apparent enhancement of BC thresholds can occur in cases of superior canal dehiscence (see Chapter 4).
类似地，当外耳道被压耳式耳机堵塞时，低频率的骨导阈值也会增强。这种低频骨导增强，即堵耳效应，在遮挡非测试耳时必须加以考虑，以决定是否在骨导测试期间施加掩蔽噪声。但是，当在施加掩蔽噪声时，使用将泡沫塞深插入耳道的插入耳机，其低频增强量比使用压耳式耳机的要小（Dean和Martin，2000）。此外，在上半规管裂的病例下，骨导阈值也会出现明显的增强。（见第四章）
Special Populations
特殊人群
TINNITUS
耳鸣
Many people who come for hearing testing experience tinnitus, the sensation of hearing internal sounds when no sound is present (see Chapter 35). Tinnitus can interfere with the perception of test tones, which can lead to a large number of false-positive responses, and false-positive responses can produce an inaccurate (too sensitive) threshold estimation. Some listeners simply require additional instruction and encouragement to wait until they are more certain they have heard a test tone. In some cases, the audiologist can present a clearly audible tone at the test frequency to remind the listener of the test tone. For more intractable cases, the examiner can present a series of pulsed tones and ask the listener to count the number of tones. It is important with listeners who are giving false-positive responses to avoid a fixed presentation rhythm and to provide irregular intervals of “no trial” silence to confirm that their responses are, in fact, responses to test tones.
许多来进行听力测试的人都会有耳鸣的经历，即在没有声音时听到内部声音的感觉（见第35章）。耳鸣会干扰对测试音调的感知，这可以导致大量的假阳性反应，而假阳性反应可以产生不准确（过于敏感）的阈值评估。一些听众只需要额外的指导和鼓励，直到他们更确定听到测试音。在某些情况下，听力师可以在测试频率上给出清晰可听的音调，以提醒听者注意测试音调。对于更难处理的情况，检查者可以呈现一系列脉冲音，并要求听者计算音调的数量。对于那些给出假阳性反应的听众来说，重要的是要避免测试音调呈现固定的节奏，并提供不规则的“无测试”沉默间隔，以确认他们的反应实际上是对测试音调的反应。
In rare cases, patients have tinnitus resulting from blood flowing nearby auditory structures. Blood flowing through a vein or artery sometimes produces masking noise or “bruit” that can elevate thresholds for low-frequency tones (Champlin et al., 1990). On the audiogram, this form of tinnitus may produce an apparent sensory/neural loss. The loss occurs because the tinnitus masks AC and BC thresholds. Bruit, a recordable form of tinnitus resulting from vibrations in the head or neck, is documented by audiologists by measuring sound levels in the ear canal (Champlin et al., 1990). This problem is treatable when the problem is caused by a vein. In a case study reported by Champlin et al. (1990), the patient received some reduction in tinnitus loudness before surgery by applying pressure to her neck. Surgical ligation of the vein responsible for the tinnitus was shown to be an effective treatment. Surgery reduced tinnitus loudness, SPLs of the bruit measured in the ear canal were lower, and the audiogram showed significantly improved thresholds.
在极少数情况下，病人耳鸣是由于听觉结构附近的血流引起的。流经静脉或动脉的血液有时产生掩蔽噪声或“杂音”，这种情况会提高低频音的阈值（Champlin等人，1990）。在听力图中，这种形式的耳鸣可能产生明显的感音/神经性损失。因为耳鸣会掩盖气导和骨导阈值，所以会发生损失。杂音是一种可记录的由头或颈部振动引起的耳鸣，听力学家通过测量耳道内的声级记录了这种情况（Champlin等人，1990）。当这个问题由静脉引起时是可以治疗的。在Champlin等人（1990年）报告的一个病例研究中，病人在手术前通过对颈部施加压力来减轻耳鸣的响度。手术结扎引起耳鸣的静脉被证明是一种有效的治疗方法。手术可降低耳鸣响度，耳道杂音声压级变低，听力图上的阈值明显改善。
PSEUDOHYPACUSIS
伪聋
Pseudohypacusis, also known as functional hearing loss and nonorganic hearing loss, is the name applied to intra-test and inter-test inconsistencies that cannot be explained by medical examinations or a known physiologic condition (Ventry and Chaiklin, 1965). Most persons who present with this condition are feigning a hearing loss for monetary or psychological gain, but a very small percentage of persons have subconscious motivations related to psychological problems (see Chapter 33).
伪聋，也被称为功能性听力损失和非器质性听力损失，是不能用医学检查或已知的生理状况来解释的测试内和测试间不一致的名称（Venter和Chaiklin，1965）。大多数患有这种情况的人为了金钱或心理上的利益而假装听力丧失，但极少数人有与心理问题有关的潜意识因素（见第33章）。
Persons presenting with pseudohypacusis are often identified from inconsistencies in their responses to the puretones. In addition to general poor reliability during threshold searches, there is a tendency for the threshold to become poorer as more presentations are made (Green, 1978). Methods of identifying the pseudohypacusis by comparing PT thresholds with other measures and the use of special tests are covered in Chapter 33.
表现伪聋的人通常从他们对纯音不一致的反应中辨别出来。除了在阈值搜索期间的一般较差的可靠性之外，随着更多的呈现，阈值有变差的趋势（Green，1978）。通过比较纯音阈值与其他测量值以及使用特殊测试来识别伪聋的方法将在第33章介绍。
AUDITORY NEUROPATHY
听神经病
Auditory neuropathy (or auditory dys-synchrony) is a condition that may account for 11% of hearing losses found in children at risk for hearing loss (Rance et al., 1999). Information about this disorder may be found in Chapters 13 and 19. Many of these children appear to be severely hard of hearing because of very poor speech recognition; however, PT thresholds do not follow any specific pattern. Puretone hearing thresholds for these children range from minimal to profound losses. Individuals with auditory neuropathy classically show very inconsistent audiometric responses during a test and between tests.
听神经病变（或听觉不同步）可能占儿童听力损失的11% (Rance et al.，1999)。有关这种疾病的信息可以在第13章和第19章找到。由于言语识别非常差，这些孩子中的许多人看起来都有严重的听力障碍。但是，纯音阈值不遵循任何特定模式。这些儿童的纯音听力阈值范围可以从最小值到严重损失。患有听觉神经病变的人通常在同一测试期间与多项测试之间表现出非常不一致的听觉反应。
AGING
老龄化
Presbycusis is a term that describes the gradual loss of hearing sensitivity that occurs in most individuals as they grow older. Studies suggest (Schuknecht, 1974; Dubno et al., 2013) that several different types of damage can occur to the auditory system because of aging. Hearing loss due to aging typically causes a gently sloping, high-frequency sensory/ neural hearing loss that tends to be slightly greater in men than in women. Figure 3.11 shows the average amount of threshold elevation expected based on aging in men who have had limited exposure to intense sounds. Even among this select group of participants, large individual differences are often observed.
老年性聋是一个术语，是用来描述大多数人随着年龄的增长听力敏感度逐渐丧失的术语。研究表明（Schuknecht，1974年；Dubno等人，2013年），由于衰老，听觉系统可能发生几种不同类型的损害。由于年龄增长导致的听力损失通常导致平缓倾斜的高频感觉/神经性听力损失，男性听力损失往往比女性略高。图3.11显示了有限地接触到强烈声音的男性，随着年龄增长，阈值的平均上升幅度。即使在这组被选中的参与者中，也经常观察到巨大的个体差异。
图3.11不同年龄的成年男性的平均听力图。 数据来自国家耳聋研究所和其他交流障碍研究所（2005年）。
ACOUSTIC TUMORS
听神经瘤
An acoustic tumor (acoustic neuroma/neurinoma or vestibular schwannoma) is a rare disorder. Once identified, these tumors are usually removed surgically, because they can compress the brainstem and threaten life. Early diagnosis and removal lessen the risk of complications during surgery and increase the opportunity to preserve hearing if that approach is pursued.
听神经瘤（听神经瘤/神经鞘瘤或前庭神经鞘瘤）是一种罕见的疾病。一旦确诊，这些肿瘤通常可通过手术切除，因为它们会压迫脑干，威胁生命。早期诊断和切除可以降低手术中并发症的风险，并且可以增加保持听力的机会。
Magnetic resonance imaging (MRI) is the definitive test for acoustic tumors. Unfortunately, it is expensive and only becomes cost effective when a screening test is used to assess which patients should receive an MRI. Puretone audiometry should be considered as part of that screening procedure. When the auditory nerve is compressed by the tumor, it often, but not always (Magdziarz et al., 2000), results in a unilateral or asymmetrical hearing loss. Because the fibers on the outside of the auditory nerve code high frequencies, the hearing loss is associated with the high frequencies (Schlauch et al., 1995). Studies have shown that a screening test that compares the average threshold difference between ears for 1, 2, 4, and 8 kHz is most effective (Schlauch et al., 1995). Threshold differences between ears for this PTA that exceed 15 dB or 20 dB maximize identification of persons with these tumors while minimizing false-positive diagnoses of persons with cochlear losses. The pass–fail criterion (e.g., requiring a 20-dB difference between ears) may differ depending on the money available for follow-up tests. A pass–fail criterion requiring 15-dB or greater differences between ears identifies more tumors than one requiring 20-dB or larger differences, but the smaller difference also yields more false-positive responses. False-positive responses (in this case, persons with cochlear losses identified incorrectly as having tumors) place a burden on the healthcare system, because follow-up tests such as MRI or auditory-evoked potentials are expensive.
磁共振成像（MRI）是听神经瘤的确诊手段。遗憾的是，它很昂贵，并且只有在使用筛选检查评估哪些患者应该接受MRI时才具有成本效益。纯音测听应该被认为是筛选程序的一部分。当听神经被肿瘤压迫时，通常但不总是（Magdziarz et al.， 2000）导致单侧或不对称的听力损失。由于听觉神经外部的神经纤维对高频进行编码，因此听力损失与高频有关（Schlauch et al.，1995）。研究表明，比较1、2、4和8Hz之间的平均阈值差异的筛选检查是最有效的（Schlauch et al.， 1995）。超过15db或20db的PTA的耳间阈值差异可以最大限度地识别这些肿瘤患者，同时最大限度地减少耳蜗损失患者的假阳性诊断。通过-未过标准（例如，要求两耳之间相差20分贝）可能会因后续检查的可用资金而有所不同。两耳间15dB或更大差异的通过-未过标准比两耳间20dB或更大差异的标准能识别更多的肿瘤，但是较小差异也产生更多的假阳性反应。假阳性反应（在这种情况下，耳蜗受损的人被错误地认定为患有肿瘤）给医疗系统带来了负担，因为后续的检查，如核磁共振成像（MRI）或听觉诱发电位（auditor- evpotential），成本高昂。
The effectiveness of a screening test based on the threshold asymmetries between ears is dependent on the clinical population. This test was found to be ineffective in a Veterans Administration hospital where many patients are males who have presbycusis and noise-induced hearing loss (NIHL) (Schlauch et al., 1995). By contrast, preliminary data from young women with normal hearing in their better ear suggest that true-positive rates and false-positive rates for this test are comparable to those for auditory brainstem response (Schlauch et al., 1995). It should also be noted that a small percentage of persons (<3%) with acoustic tumors have no hearing loss or hearing threshold asymmetry (Magdziarz et al., 2000).
基于耳间阈值不对称的筛选试验的有效性取决于临床人群。这项测试在退伍军人管理局医院被发现是无效的，在那里许多患者是男性，他们有老年性耳聋和噪声性听力损失（NIHL）（Schlauch et al.， 1995）。相比之下，来自听力正常的年轻女性的初步数据表明，该测试的真阳性率和假阳性率与听觉脑干反应的真阳性率和假阳性率相当（Schlauch et al.，1995）。还应注意的是，有一小部分（<3%）听神经瘤患者没有听力损失或没有听力阈值不对称（Magdziarz et al.，2000）。
MÉNIÈRE’S DISEASE
梅尼埃病
Ménière’s disease is diagnosed based on the symptoms of sensory/neural hearing loss, vertigo, tinnitus, and aural fullness (Committee on Hearing and Equilibrium, 1995) as well as the exclusion of other known diseases. Adding to the diagnostic challenge, the four symptoms do not occur all at once, and some of them may occur only during the intermittent attacks that characterize this disease. It takes, on average, 1 year after the first symptom occurs before all of the symptoms are experienced by a person stricken with this disease. Ménière’s disease rarely occurs before age 20 and is most likely to begin between the fourth and sixth decades (Pfaltz and Matefi, 1981).
梅尼埃病的诊断依据是感音/神经性听力损失、眩晕、耳鸣和耳闷症状（听力和平衡委员会，1995年），以及排除其他已知疾病。诊断困难的是，这四种症状并不是同时出现的，其中一些症状可能只在这种疾病的间歇性发作期间出现。平均来说，在第一个症状出现后的1年内，患者才能经历到这种疾病的所有症状。梅尼埃病很少发生在20岁之前，最可能发生在40岁至60岁之间。（Pfaltz and Matefi, 1981）
Ménière’s disease usually begins as a unilateral sensory/ neural hearing loss, but the frequency of bilateral involvement increases with disease duration (Stahle and Klockhoff, 1986). Although audiometric configuration is not too helpful in diagnosing Ménière’s disease, a peaked audiogram (described in Table 3.3) is most common (roughly 60% of involved ears), and a rising audiogram is also seen quite frequently, especially in the earliest stages of the disease. However, the peaked audiogram is also seen in 13% of ears with acoustic tumors (Ries et al., 1998).
梅尼埃病通常以单侧感觉/神经性听力损失开始，但随着病程的延长，双侧受累的频率增加（Stahle和Klockhoff，1986）。虽然听力曲线对梅尼埃氏病的诊断没有太大帮助，但峰值听力图（表3.3中描述）是最常见的，而且上升的听力图也很常见（大约占受累耳朵的60%），特别是在疾病的早期阶段。然而，13%的听神经瘤患者的听力图也出现峰值听力图。
NOISE-INDUCED HEARING LOSS AND ACOUSTIC TRAUMA
噪声性聋与声损伤
Exposure to intense sound levels can cause permanent or temporary hearing loss due to hair cell damage. When a narrowband sound is presented at a level high enough to result in damage, a loss occurs at a frequency roughly one-half octave above the frequency of exposure (Henderson and Hamernik, 1995). Most people who are exposed to damaging noise levels in their work or recreational endeavors are exposed to broadband sounds, but their losses, especially during early stages of NIHL, are characterized by a “notch” (a drop in hearing) on the audiogram. The greatest hearing loss typically occurs in the region of 3,000 to 6,000 Hz. The susceptibility of these frequencies is a result of sound amplification by the external ear (Gerhardt et al., 1987). The amplification is mainly a result of the ear canal resonance, which increases the level of sound by 20 dB or more. Temporary hearing loss is referred to as temporary threshold shift (TTS), and permanent changes are referred to as permanent threshold shifts (PTS).
暴露于强烈的声级下可能会由于毛细胞损伤而导致永久性或暂时性听力损失。当窄带声音的音量高到足以造成损坏时，损失的频率大约在曝光频率后面的半倍频程上。大多数在工作或娱乐活动中暴露于破坏性噪音水平的人都会接触到宽带声音，但是他们的损失，特别是在噪声性聋的早期阶段，其特点是听力图上有一个“凹槽”（听力下降）。最严重的听力损失通常发生在3，000至6，000赫兹之间。这些频率的敏感性是外耳放大声音的结果。放大主要是耳道共振的结果，可使声级提高20dB或更多。暂时性听力损失称为暂时性阈移（TTS），永久性改变称为永久性阈移（PTS）。
The greater variability of thresholds at 6 and 8 kHz than at other frequencies makes small noise notches associated with early NIHL difficult to identify. Some frequently used rules for quantifying noise notches can produce high falsepositive rates when decisions are based on a single audiogram (Schlauch and Carney, 2011). Averaging multiple audiograms improves diagnostic accuracy as does clearing the ear canals of all earwax, which can result in the appearance of a high-frequency loss (Jin et al., 2013; Schlauch and Carney, 2012). NIHL can be slowly progressive, as listeners are exposed to high sound levels over months and years (Ward et al., 2000), or it can rapidly change, such as noise trauma after a sudden explosion or impulsive sound (Kerr and Byrne, 1975; Orchik et al., 1987). The shooting of a rifle can result in a greater loss in the ear closest to the muzzle of the gun. In right-handed persons, the left ear is exposed directly to the muzzle, and the right ear is protected from the direct blast by the head. New evidence (Kujawa and Liberman, 2009) suggests that PT thresholds may return to near normal following noise exposure, whereas functional auditory abilities may remain compromised due to the noise exposure. (See Chapter 32 for NIHL.)
在6 kHz和8 kHz的阈值比在其他频率有更大的变异性，使得与早期噪声性聋相关联的小噪声切迹难以识别。当决策基于单个听力图时，一些常用的量化噪声切迹的规则可以产生高的假阳性率（Schlauch和Carney，2011年）。多次听力图的平均值可以提高诊断的准确性，如同清除所有耳道内的耳垢会提高诊断准确性，这些耳垢会导致高频损耗。噪声性聋可以缓慢进展，因为听者在数月或数年的时间里都暴露在高强度的声级中（Ward et al.， 2000），也可以快速变化，例如突然爆炸后或脉冲声的噪音创伤。步枪的射击会使靠近枪口的耳朵损失更大。在惯用右手的人中，左耳直接暴露于枪口，右耳受到头部保护免于直接受到冲击。新的证据显示，在噪声暴露后纯音阈值可能会恢复到接近正常水平，而功能性听觉能力可能会因噪声暴露而仍然受损。（NIHL见第32章。）
OTOTOXICITY
耳毒性
Regular monitoring of PT thresholds is particularly important for patients who take drugs known to be ototoxic. For example, certain powerful antibiotics and cancer-fighting drugs are known to cause cochlear and vestibular damage in many patients. Monitoring hearing sensitivity during treatment could allow a physician to consider alternative treatments that might preserve hearing. Ototoxic drugs typically cause reduction in high-frequency hearing before having any adverse effect on hearing for the speech range. For this reason, extended high-frequency hearing testing is recommended for ototoxic monitoring test protocols. Several studies have demonstrated the effectiveness of early identification of ototoxic hearing loss by monitoring thresholds for frequencies higher than 8,000 Hz (Fausti et al., 1992). However, for ototoxic drugs that selectively damage inner hair cells in the cochlea (e.g., carboplatin), PT thresholds may be unaffected even though extensive damage has occurred (Lobaranis et al., 2013).
定期监测纯音阈值对于服用已知具有耳毒性药物的患者尤为重要。例如，已知某些强效抗生素和抗癌药物会在许多患者造成耳蜗和前庭损伤。在治疗期间监测听力敏感性可让医生考虑可能保留听力的替代治疗。在对言语范围的听力产生任何不利影响之前，耳毒性药物通常会导致高频听力降低。因此，耳毒性监测测试方案中建议对扩展的高频进行听力测试。一些研究已经证明通过监测8,000 Hz以上频率的阈值来早期识别耳毒性听力损失的有效性。然而，对于选择性损害耳蜗内毛细胞的耳毒性药物，即使发生了广泛的损伤，纯音阈值也可能不受影响。
OTITIS MEDIA
中耳炎
Young children are susceptible to temporary, recurring middle-ear inflammations (otitis media) that are often accompanied by fluid in the middle ear (effusion). Otitis media, often referred to as a middle-ear “infection,” may be viral or bacterial but is most often serous (noninfected fluid). Otitis media is the most common medical diagnosis for children, accounting for 6 million office visits in 1990 for children between the ages of 5 and 15 years (Stoll and Fink, 1996). Adults, too, may have otitis media with effusion, although the prevalence decreases significantly with age (Fria et al., 1985). During the active infection, often lasting a month or more, a patient’s hearing loss may fluctuate, usually varying between 0 and 40 dB. The average degree of hearing loss is approximately 25 dB. Figure 3.8, which was used earlier in this chapter to illustrate an audiogram for a conductive loss, shows an audiogram derived from the average thresholds from a group of children diagnosed with otitis media.
幼儿易患暂时性的、反复发作的中耳炎症（中耳炎），中耳炎常伴有中耳积液（积液）。中耳炎，通常被称为中耳“感染”，可能是病毒性或细菌性，但最常见的是浆液性（非感染液体）。中耳炎是儿童最常见的医学诊断，1990年，5 - 15岁儿童共有600万人次就诊（Stoll and Fink, 1996）。成年人也可能患有分泌性中耳炎，尽管其发病率随着年龄的增长而显著下降（Fria et al.，1985）。在感染发作期，通常持续一个月或更长时间，患者的听力损失可能出现波动，通常在0至40分贝之间变化。平均听力损失约为25分贝。图3.8是本章前面用来说明传导性损失的听力图，它显示了一组诊断为中耳炎的儿童的平均阈值。
TYMPANIC MEMBRANE PERFORATIONS
鼓膜穿孔
Tympanic membrane perforations are caused by trauma, disease, or surgery. The diameter and location of perforation and the involvement of other middle-ear structures determine the amount of conductive hearing loss, if any. For instance, a myringotomy and the placement of pressureequalization tubes represent a physician-induced perforation that results in a minimal air–bone gap in successful surgeries.
鼓膜穿孔是由外伤、疾病或手术引起的。如果有的话，穿孔的直径和位置以及其他中耳结构的参与决定了传导性听力损失量的程度。例如，鼓膜切开术和鼓膜置管代表了一种医生诱导的穿孔，在手术成功后会导致最小的气骨间隙。
The measurement of AC thresholds in the presence of tympanic membrane perforations requires special consideration. Figure 3.12 shows an audiogram obtained in a single session from a school-age child who has a tympanic membrane perforation in the left ear and a pressure-equalization tube in the right ear. Thresholds were measured twice in each ear, once with supra-aural earphones and again with insert earphones. Note that the low-frequency thresholds obtained from insert earphones were as much as 15 to 25 dB poorer than the ones obtained with supra-aural earphones. This outcome is typical and is predicted because insert earphones are more susceptible to calibration problems in the presence of perforations than are supra-aural earphones when calibration is based on coupler rather than real ear measurements (Voss et al., 2000). The thresholds obtained using the supra-aural earphones are more accurate in this instance and in any situations in which the effective volume of the ear canal is significantly larger than is typical.
在鼓膜穿孔的情况下，测量纯音阈值需要特殊考虑。图3.12显示了一个学龄儿童在一次治疗中测到的听力图，该儿童左耳有鼓膜穿孔，右耳有鼓膜置管。每只耳朵中测量两次阈值，一次使用压耳式耳机，另一次使用插入式耳机。请注意，从插入式耳机获得的低频阈值比用压耳式耳机获得的低15至25dB。这种结果是典型的并且是可以预测的，因为当校准基于耦合器而不是真耳测量时，插入式耳机比压耳式耳机更容易在穿孔的情况下出现校准问题（Voss等，2000）。在这种情况下以及在任何耳道有效容积明显大于典型的情况下，使用压耳式耳机获得的阈值更准确。
图3.12同一儿童双侧穿孔两种耳机的听力图。
Relation between Puretone Thresholds and Speech Measures
纯音阈值与言语测试的关系
PT thresholds are often compared with speech audiometric test results. The two most common comparisons are with speech reception thresholds (SRT) and suprathreshold word-recognition scores (WRSs). (See Chapter 5 for a comprehensive review of speech audiometry.)
纯音阈值通常与言语听力测试结果进行比较。两个最常见的比较是言语接受阈（SRT）和阈上单词识别率（WRSs）。（有关言语测听的全面回顾，请参见第5章。）
SRTs obtained using spondaic words (or spondees) agree well with PT thresholds for low frequencies. Spondees are easily recognized; listeners only need to recognize the vowels to identify these words correctly. Because of the importance of the vowels at low intensities, spondee thresholds are found to agree closely with the average of PT thresholds for 500 and 1,000 Hz (Carhart and Porter, 1971). In the event of a rising audiogram, better agreement between the spondee and PT thresholds is the average for 1,000 and 2,000 Hz. Spondee thresholds and a two-frequency PTA, as noted earlier, nearly always agree within ±10 dB in cooperative examinees. This agreement makes the threshold for spondaic words an excellent check on the validity and reliability of the audiogram. This comparison is important for most children. It is also a valuable tool for assessing the reliability of PT thresholds in adults who demonstrate inconsistent puretone responses or who may present with pseudohypacusis (Schlauch et al., 1996).
使用扬扬格单词（扬扬格词/双音节词）获得的SRTs与低频纯音阈值一致。扬扬格词很容易识别；听者只需要识别元音就可以正确识别这些单词。由于低强度时元音的重要性，扬扬格词阈值与500和1000 Hz的纯音阈值的平均值非常接近（Carhart and Porter, 1971）。在上升的听力图中，扬扬格词和纯音阈值之间更好的一致性是1000和2000 Hz的平均值。扬扬格词阈值和如前所述的双频PTA在合作参与者中几乎总是在±10dB内一致。这一协议使扬扬格词的阈值对听力图的有效性和可靠性进行了极好的检验。这种比较对大多数孩子都很重要。它也是评估成人纯音阈值可靠性的有价值的工具，这些成人表现出不一致的纯音反应或可能存在伪聋。
Suprathreshold word-recognition performance is assessed in most clinical settings by scoring a client’s ability to repeat back a list of monosyllabic words. WRSs provide a valid estimate of speech understanding ability (Wilson and Margolis, 1983) and quantification of the distortion, if any, caused by sensory/neural hearing loss. WRSs are correlated with puretone audiometric thresholds in persons with cochlear losses (Pavlovic et al., 1986), but individuals’ scores vary considerably depending on the type of damage to the auditory system. If the words are presented at a level high enough to make the speech sounds audible (overcoming the attenuation caused by the loss), persons with mild cochlear hearing loss are expected to have high WRSs, and those with severe to profound losses are likely to have fairly low scores. Dubno et al. (1995) and Yellin et al. (1989) have published tables relating WRSs and the average of PT thresholds for 500, 1,000, and 2,000 Hz for groups of persons with typical cochlear losses. WRSs that are abnormally low for a given PTA are associated with a variety of conditions including an acoustic tumor, multiple sclerosis, Ménière’s disease, auditory neuropathy, and cochlear dead regions (Moore, 2004), to name a few. When there are dead regions (areas of missing inner hair cells in the cochlea), PT thresholds may appear artificially better than expected because of the spread of energy along the cochlea. Healthier cochlear cells adjacent to the missing cells will elicit a response to puretones presented at the dead region frequency.
在大多数临床环境中，阈上单词识别性能是通过对患者重复单音节单词的能力来评估的。WRSs提供了对言语理解能力的有效评估（Wilson and Margolis, 1983），并量化了由感音神经听力损失引起的失真 （如果有的话）。WRS与耳蜗损伤者的纯音听阈相关（Pavlovic et al., 1986），但个体的分数因听觉系统损伤类型的不同而有很大差异。如果这些单词音量足够高，使语音可以听到（克服了损耗引起的衰减），那么轻度耳蜗听力损失的人预计会有较高的WRSS，而重度至极重度损失的人可能会有相当低的分数。Dubno et al.，（1995）和Yellin et al.（1989）发表了关于典型耳蜗损伤人群WRSs与500、1000、2000 Hz纯音阈值平均值关系的表。对于给定PTA而言，异常低的WRSs与多种疾病有关，包括听神经肿瘤、多发性硬化症、梅尼埃病、听神经病变和耳蜗死区等等（Moore，2004）。当存在死区（耳蜗内毛细胞缺失的区域）时，由于能量沿着耳蜗的扩散，纯音阈值可能比预期的要高。与缺失细胞相邻的健康耳蜗细胞会对死区频率的纯音作出响应。
Automated Audiometry
自动听力测定
Clinical researchers automated the measurement of routine hearing thresholds to increase clinical efficiency (Rudmose, 1963). Devices were developed for this purpose, and several machines were manufactured and sold commercially. Some of these automated audiometers had the ability to vary intensity and frequency during a hearing test.
临床研究人员自动化了常规听力阈值的测量以提高临床效率（Rudmose, 1963）。为此研制了一些设备，制造了几台机器并进行了商业销售。其中一些自动测听仪能够在听力测试中改变强度和频率。
The Bekesy audiometer is an automated audiometer that was a common piece of equipment in major clinical and research settings in the 1960s. In its routine application, AC thresholds were assessed for interrupted tones and sustained tones for frequencies ranging from 100 to 10 kHz. Frequencies were swept through the range over time, typically at a rate of one octave per minute. The examinee controlled the level of the sound by depressing a handheld switch for as long as he or she heard a tone and released it when none was heard. The resulting brackets around threshold were recorded on an audiogram. Patterns of responses for sustained tones and interrupted tones were found to distinguish between different etiologies of hearing loss (see Chapter 33 on pseudohypacusis). In recent years, the use of Bekesy audiometry has decreased in medical settings, but it still has important applications in research, the military, and in hearing conservation programs.
贝克西（Bekesy）听力计是一种自动化听力计，20世纪60年代主要临床和研究环境中的常用设备。在它的常规应用中，100-10khz的中断音调和持续音调作为气导阈值评估。频率在一段时间内扫过整个范围，通常以每分钟一个倍频程的速度扫过。受检者只要听到一种声音，就按下手持开关来控制音量，当听不到时，就释放控制开关。由此产生的阈值被记录在听力图上。持续音调和间断音调的反应模式被发现可以区分听力损失的不同病因（见第33章关于伪聋）。近年来，贝克西听力计在医学环境中的使用有所减少，但在研究，军队和听力保护项目中仍有重要应用。
Within the past few years, a new generation of automated audiometers has been developed (Margolis et al., 2010). The new automated audiometers are capable of measuring masked AC and BC thresholds, as well as WRSs, with only a single placement of the earphones and BC oscillator. Bekesy audiometry is still used along with some other automated methods (Laroche and Hetu, 1997), including ones that implement the threshold-finding procedure used in manual puretone audiometry (Margolis et al., 2010). Computer- based rules control the presentation of stimuli, examinee responses, and the plotting of thresholds. The goal is to automate threshold collection for routine cases, which will free audiologists to perform more complex measures or to work with difficult-to-test populations.
在过去的几年里，新一代的自动测听仪已经开发出来（Margolis et al.，2010）。新的自动测听仪能够测量掩蔽的气导和骨导阈值，以及WRSs，只需要放置一个耳机和骨导振荡器。贝克西听力计仍然与其他一些自动化方法一起使用（Laroche and Hetu, 1997），包括实现手工纯音测听中使用的阈值查找程序的方法（Margolis et al.， 2010）。基于计算机的规则控制刺激的呈现、受试者的反应和阈值的绘制。目标是自动收集常规病例的阈值，这将使听力学家得以执行更复杂的测量，或与测试困难的人工作。
Calibration
校准
Clinical data require accurate stimulus specification, or the results are meaningless. When most persons think of calibration of audiometers, the obvious examples include the accuracy of puretone frequency and level. However, puretone calibration involves much more, including an assessment of attenuator linearity, harmonic distortion, rise and fall times, and more. Consult ANSI (2010) and Chapter 2 on calibration in this book to learn more about this topic.
临床数据需要精确的刺激指标，否则结果毫无意义。当大多数人想到听力计的校准时，最明显的例子包括纯音频率和音量的准确性。然而，纯音校准涉及更多，包括衰减器线性度，谐波失真，上升和下降时间等的评估。有关此主题的更多信息，请参阅ANSI（2010）和本书中有关校准的第2章。
Puretone Thresholds and the Audiologic Test Battery
纯音阈值与听力测试组合
PT thresholds are measured on nearly everyone entering a diagnostic audiology clinic, but the test sequence and the extent of the measurements often differ across clinics. Most of these differences in protocol are implemented to save testing time, which contributes to the cost of running a clinic. ASHA’s guide to manual PT threshold audiometry (2005) makes no recommendation concerning the puretone test sequence. In 2000, the Joint Audiology Committee on Practice Algorithms and Standards recommended an algorithm that listed puretone AC testing (with appropriate masking applied) followed by puretone BC testing with appropriate masking. They acknowledged that the assessment process may vary “based on patient need and the assessment setting.” Furthermore, they stated that “decision-making . . . occurs(s) throughout this process.”
纯音阈值是几乎所有进入听力学诊所就诊的患者都要测量的，但是测试顺序和测量的范围往往因诊所而异。这些协议上的差异大部分是为了节省测试时间而实现的，这有助于节省诊所的运营成本。ASHA的人工纯音阈值测试指南（2005）对纯音测试顺序没有给出任何建议。2000年，实践算法和标准联合听力委员会建议采用一种算法，列出纯音气导测试 （应用适当的掩蔽），然后使用适当的掩蔽方法进行纯音骨导测试。他们承认，评估过程可能会根据“病人的需要和评估环境”而有所不同。此外，他们还说“决策……在整个过程中发生。”
Based on informal surveys of clinicians in a variety of settings, it seems that there is considerable variability in test protocols among clinics. In many clinics, BC thresholds are not usually obtained from persons with normal AC thresholds (near 0 dB HL) unless the case history or risk of middle-ear problems suggests otherwise. BC threshold testing is also omitted in some clinics for returning patients with pure sensory/neural losses if their AC thresholds match those of the prior visit. A common alternative test sequence is to begin with puretone AC thresholds followed by suprathreshold word-recognition testing. After word-recognition testing, BC thresholds are measured. Although it would be useful to have puretone BC thresholds prior to AC thresholds to know how much masking noise can be presented safely, this advantage is outweighed by the inconvenience of having to enter the booth multiple times to reposition the BC vibrator and earphones. Valid, masked AC thresholds can be obtained successfully from most clients before obtaining BC thresholds.
根据在不同环境下对临床医生的非正式调查，各诊所之间的测试方案似乎存在相当大的差异。在许多诊所中，骨导阈值通常不是从具有正常气导阈值（接近0 dB HL）的人获得的，除非有中耳问题相关病史或风险。在一些诊所，单纯感音/神经性损失的患者如果其气导阈值与之前的检查值相匹配，那么骨导阈值测试会被省略。一种常见的替代测试顺序是从纯音气导阈值开始，然后进行阈上单词识别测试。经过单词识别测试，测得骨导阈值。虽然在气导阈值之前设置纯音骨导阈值会很有用，以了解多少掩蔽噪声是安全的，但这一优势被不得不多次进入测听室重新定位骨导振动器和耳机的不便所抵消。有效的、掩蔽的气导阈值可以在得到骨导阈值之前从大多数测试者那里成功获取。
A few clinics begin with immittance testing, which usually includes a tympanogram and acoustic reflex thresholds. If the case history does not indicate a middle-ear problem and these tests of middle-ear function are normal, then BC thresholds may not be performed, and the loss, if present, is assumed to be a sensory/neural loss. A possible risk of this strategy is that, in rare instances, persons with middle-ear problems have normal immittance measures. In this situation, a conductive loss would be missed. This approach also adds the expense of immittance testing for each client. Studies should be done using an evidence-based practice model to determine whether the assessment of middle-ear status of each client using immittance or wideband reflectance (see Chapter 9) is justified. Another time-saving strategy might be to measure BC thresholds at two frequencies, a low and a high frequency, and if an air–bone gap is not observed, BC thresholds are not measured for other frequencies. A low frequency, such as 500 Hz, would assess stiffness-related middle-ear pathologies. A high frequency, such as 4,000 Hz, would identify mass-related middle-ear pathologies and collapsed canals. Since this method requires placement of the BC vibrator, the amount of time actually saved would be limited.
一些诊所从导抗测试开始，通常包括鼓室图和声反射阈值。如果病史没有提示中耳问题，并且中耳功能测试正常，则可能不再进行骨导阈值测试，如果出现听力下降，则假定为感音/神经性损失。这种方法的一个可能风险是，在极少数情况下，有中耳问题的人具有正常的导抗测试值。在这种情况下，传导性损失会被忽略。这种方法还增加了每个受试者的导抗测试费用。应使用基于证据的实践模型进行研究，以确定是否使用导抗或宽带反射评估每个患者的中耳状态（见第9章）。另一种节省时间的策略可能是在两个频率测量骨导阈值，一个低频率和一个高频率，如果没有观察到气骨间隙，则不会测量其他频率的骨导阈值。低频（如500hz）可评估与硬化有关的中耳病变。高频，例如4000赫兹，可以识别与肿块有关的中耳病变和耳道塌陷。由于此方法需要放置骨导振子，所以实际节省的时间是有限的。
Despite the observed variability, it seems that it is possible for audiologists to obtain important diagnostic information about the degree, type, and configuration of hearing losses using a variety of valid, evidence-based puretone audiometric methods. Although at first glance, the puretone test procedure may appear elementary, it is clear that well-informed test procedures using appropriate and calibrated test equipment provide a necessary part of the complete audiologic test battery and form the basis for clinical decision making.
尽管存在观察变异性，但听力学家似乎可以使用各种有效的、基于证据的纯音听力测定方法获得关于听力损失的程度、类型和配置的重要诊断信息。虽然乍一看，纯音测试程序可能很基础，但很明显，采用适当和校准的测试设备进行的测试提供了完整的听力测试组合的必要部分，并形成临床决策的基础。
FOOD FOR THOUGHT
引人深思的事
Given the known test–retest variability of PT thresholds, what is the threat to the quality of a hearing conservation program if the tester chooses not to make multiple estimates of baseline audiograms?
1． 鉴于纯音阈值的已知测试重测变异性，如果测试人员选择不对基线听力图进行多次评估，对听力保护程序的质量有何威胁？
Think about examples of auditory pathology where the PT threshold might be misleading, when it might not reflect the full nature of the underlying cochlear injury.
思考下听觉病理学的例子，其中纯音阈值可能具有误导性，而纯音阈值可能不会反映潜在耳蜗损伤的全部性质。
Consider several cases where the ear canal volume (the volume under the earphone) might significantly affect the resulting PT threshold. Consider the client’s total volume of the outer ear, perforations of the eardrum, and possible occlusions in the ear canal. What effect will these have on the resulting thresholds?
考虑几种情况，耳道容积（耳机下的音量）可能会显着影响最终的纯音阈值。考虑患者的外耳总容积、鼓膜穿孔以及可能的耳道阻塞情况。这些对最终的阈值产生什么影响？
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