SpeechRecognitionEngine.RecognizeAsync Method


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Starts an asynchronous speech recognition operation.

Namespace:   System.Speech.Recognition
Assembly:  System.Speech (in System.Speech.dll)


Performs a single, asynchronous speech recognition operation.


Performs one or more asynchronous speech recognition operations.

These methods perform single or multiple, asynchronous recognition operations. The recognizer performs each operation against its loaded and enabled speech recognition grammars.

During a call to this method, the recognizer can raise the following events:

To retrieve the result of an asynchronous recognition operation, attach an event handler to the recognizer's SpeechRecognized event. The recognizer raises this event whenever it successfully completes a synchronous or asynchronous recognition operation. If recognition was not successful, the Result property on RecognizeCompletedEventArgs object, which you can access in the handler for the RecognizeCompleted event, will be null.

An asynchronous recognition operation can fail for the following reasons:

  • Speech is not detected before the timeout intervals expire for the BabbleTimeout or InitialSilenceTimeout properties.

  • The recognition engine detects speech but finds no matches in any of its loaded and enabled Grammar objects.

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