audiocalc

A few audio/sound calculation utilities for Python.

Caution: I am not a sound engineer. This comes without any sort of guarantee. See file "LICENSE" for details.

If you find a bug, please post a remark in the issues section. Thanks!

Function overview

damping

Caclulates the damping (dissipation, absorption) in dependence of air pressure, temperature, humidity and frequency. The return value is the damping in dB/m (decibel per meter).

>>> d = audiocalc.damping(temp=20, relhum=80, freq=8000)
>>> d
0.06945538

total_level

Given sound pressure levels for octave frequencies, calculates the total sound pressure level.

>>> octave_frequencies = {
    'f63': 71.5,
    'f125': 68.5,
    'f250': 64,
    'f500': 58,
    'f1000': 53,
    'f2000': 47,
    'f4000': 40,
    'f8000': 32}
>>> audiocalc.total_level(octave_frequencies)
73.91092323

total_rated_level

Given sound pressure levels for octave frequencies, calculates the A-rated total sound pressure level.

>>> octave_frequencies = {
    'f63': 71.5,
    'f125': 68.5,
    'f250': 64,
    'f500': 58,
    'f1000': 53,
    'f2000': 47,
    'f4000': 40,
    'f8000': 32}
>>> audiocalc.total_rated_level(octave_frequencies)
60.5054659

distant_level

Given a reference sound pressure level (reference_level) in a reference_distance, this function calculates the sound pressure level at a certain distance.

The unit for sound level parameter and return value is dB, the unit for distances is meters.

Assumptions:

• No air damping
• The sound source is point-shaped
• energy spreads equally to all directions

>>> l = audiocalc.distant_level(
        reference_level=100,
        distance=100,
        reference_distance=1)
>>> l
60.00000000000001

distant_total_damped_rated_level

This combines the powers of some of the functions above. It calculates the total A-rated sound pressure level, based on a reference distance and octave sound pressure levels, given a distance, temperature and relative humidity.

>>> octave_frequencies = {
    'f63': 71.5,
    'f125': 68.5,
    'f250': 64,
    'f500': 58,
    'f1000': 53,
    'f2000': 47,
    'f4000': 40,
    'f8000': 32}
>>> audiocalc.distant_total_damped_rated_level(
    octave_frequencies=octave_frequencies,
    reference_distance=300,
    distance=2000,
    temp=20, relhum=80)
40.860935587070635

level_to_power

Converts logarithmic sound pressure level (dB) values to metric power (W/sqm) values.

>>> audiocalc.level_to_power(100)
0.01

Development

Execute the unit tests using

python -m audiocalc.test

A performance test script for the distant_total_damped_rated_level function (which makes use of other functions as well) can be executed like this:

python -m audiocalc.benchmark_damping

In order to activate profiling of the benchmark, add the -p parameter.

python -m audiocalc.benchmark_damping -p

Credits

• Christopher Arndt has helped with tremendous speedup through the use of Cython
• Some basic calculations have been adapted from http://www.sengpielaudio.com/

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