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speechrecognitionlistconstraint.md

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-api-id -api-type
T:Windows.Media.SpeechRecognition.SpeechRecognitionListConstraint
winrt class

Windows.Media.SpeechRecognition.SpeechRecognitionListConstraint

-description

A custom grammar constraint based on a list of words or phrases that can be recognized by the SpeechRecognizer object. When initialized, this object is added to the Constraints collection.

Note

Speech recognition using a custom constraint is performed on the device.

-remarks

Constraints, or grammars, define the spoken words and phrases that can be matched by the speech recognizer. You can specify one of the pre-defined, web-service grammars (SpeechRecognitionTopicConstraint) or you can create a custom grammar, described here, that is installed with your app.

  • Programmatic list constraints (SpeechRecognitionListConstraint) provide a lightweight approach to creating simple grammars using a list of words or phrases. A list constraint works well for recognizing short, distinct phrases. Explicitly specifying all words in a grammar also improves recognition accuracy, as the speech recognition engine must only process speech to confirm a match. The list can also be programmatically updated.
  • A Speech Recognition Grammar Specification (SRGS) grammar (SpeechRecognitionGrammarFileConstraint) is a static document that, unlike a programmatic list constraint, uses the XML format defined by the Version 1.0. An Speech Recognition Grammar Specification (SRGS) grammar provides the greatest control over the speech recognition experience by letting you capture multiple semantic meanings in a single recognition.

CompileConstraintsAsync must always be called before RecognizeAsync or RecognizeWithUIAsync, even if no constraints are specified in the Constraints property.

Note

You can use a SpeechRecognitionListConstraint in conjunction with a web service SpeechRecognitionTopicConstraint to increase accuracy during a dictation session by providing a set of domain-specific keywords that you think are likely to be used.

-examples

-see-also

Windows.Media.SpeechRecognition, SpeechRecognitionConstraintType, ISpeechRecognitionConstraint, Speech interactions, Speech recognition and speech synthesis sample, Holographic voice input sample