Export (0) Print
Expand All

SpeechRecognizer Class

Provides access to the shared speech recognition service available on the Windows desktop.

System.Object
  System.Speech.Recognition.SpeechRecognizer

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

'Declaration
Public Class SpeechRecognizer _
	Implements IDisposable

The SpeechRecognizer type exposes the following members.

  NameDescription
Public methodSpeechRecognizerInitializes a new instance of the SpeechRecognizer class.
Top

  NameDescription
Public propertyAudioFormatGets the format of the audio being received by the speech recognizer.
Public propertyAudioLevelGets the level of the audio being received by the speech recognizer.
Public propertyAudioPositionGets the current location in the audio stream being generated by the device that is providing input to the speech recognizer.
Public propertyAudioStateGets the state of the audio being received by the speech recognizer.
Public propertyEnabledGets or sets a value that indicates whether this SpeechRecognizer object is ready to process speech.
Public propertyGrammarsGets a collection of the Grammar objects that are loaded in this SpeechRecognizer instance.
Public propertyMaxAlternatesGets or sets the maximum number of alternate recognition results that the shared recognizer returns for each recognition operation.
Public propertyPauseRecognizerOnRecognitionGets or sets a value that indicates whether the shared recognizer pauses recognition operations while an application is handling a SpeechRecognized event.
Public propertyRecognizerAudioPositionGets the current location of the recognizer in the audio input that it is processing.
Public propertyRecognizerInfoGets information about the shared speech recognizer.
Public propertyStateGets the state of a SpeechRecognizer object.
Top

  NameDescription
Public methodDisposeDisposes the SpeechRecognizer object.
Protected methodDispose(Boolean)Disposes the SpeechRecognizer object and releases resources used during the session.
Public methodEmulateRecognize(String)Emulates input of a phrase to the shared speech recognizer, using text instead of audio for synchronous speech recognition.
Public methodEmulateRecognize(RecognizedWordUnit(), CompareOptions)Emulates input of specific words to the shared speech recognizer, using text instead of audio for synchronous speech recognition, and specifies how the recognizer handles Unicode comparison between the words and the loaded speech recognition grammars.
Public methodEmulateRecognize(String, CompareOptions)Emulates input of a phrase to the shared speech recognizer, using text instead of audio for synchronous speech recognition, and specifies how the recognizer handles Unicode comparison between the phrase and the loaded speech recognition grammars.
Public methodEmulateRecognizeAsync(String)Emulates input of a phrase to the shared speech recognizer, using text instead of audio for asynchronous speech recognition.
Public methodEmulateRecognizeAsync(RecognizedWordUnit(), CompareOptions)Emulates input of specific words to the shared speech recognizer, using text instead of audio for asynchronous speech recognition, and specifies how the recognizer handles Unicode comparison between the words and the loaded speech recognition grammars.
Public methodEmulateRecognizeAsync(String, CompareOptions)Emulates input of a phrase to the shared speech recognizer, using text instead of audio for asynchronous speech recognition, and specifies how the recognizer handles Unicode comparison between the phrase and the loaded speech recognition grammars.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodLoadGrammarLoads a speech recognition grammar.
Public methodLoadGrammarAsyncAsynchronously loads a speech recognition grammar.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodRequestRecognizerUpdateRequests that the shared recognizer pause and update its state.
Public methodRequestRecognizerUpdate(Object)Requests that the shared recognizer pause and update its state and provides a user token for the associated event.
Public methodRequestRecognizerUpdate(Object, TimeSpan)Requests that the shared recognizer pause and update its state and provides an offset and a user token for the associated event.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodUnloadAllGrammarsUnloads all speech recognition grammars from the shared recognizer.
Public methodUnloadGrammarUnloads a specified speech recognition grammar from the shared recognizer.
Top

  NameDescription
Public eventAudioLevelUpdatedOccurs when the shared recognizer reports the level of its audio input.
Public eventAudioSignalProblemOccurredOccurs when the recognizer encounters a problem in the audio signal.
Public eventAudioStateChangedOccurs when the state changes in the audio being received by the recognizer.
Public eventEmulateRecognizeCompletedOccurs when the shared recognizer finalizes an asynchronous recognition operation for emulated input.
Public eventLoadGrammarCompletedOccurs when the recognizer finishes the asynchronous loading of a speech recognition grammar.
Public eventRecognizerUpdateReachedOccurs when the recognizer pauses to synchronize recognition and other operations.
Public eventSpeechDetectedOccurs when the recognizer detects input that it can identify as speech.
Public eventSpeechHypothesizedOccurs when the recognizer has recognized a word or words that may be a component of multiple complete phrases in a grammar.
Public eventSpeechRecognitionRejectedOccurs when the recognizer receives input that does not match any of the speech recognition grammars it has loaded.
Public eventSpeechRecognizedOccurs when the recognizer receives input that matches one of its speech recognition grammars.
Public eventStateChangedOccurs when the running state of the Windows Desktop Speech Technology recognition engine changes.
Top

Applications use the shared recognizer to access Windows Speech Recognition. Use the SpeechRecognizer object to add to the Windows speech user experience.

This class provides control over various aspects of the speech recognition process:

The configuration of Windows Speech Recognition is managed by the use of the Speech Properties dialog in the Control Panel. This interface is used to select the default desktop speech recognition engine and language, the audio input device, and the sleep behavior of speech recognition. If the configuration of Windows Speech Recognition is changed while the application is running, (for instance, if speech recognition is disabled or the input language is changed), the change affects all SpeechRecognizer objects.

To create an in-process speech recognizer that is independent of Windows Speech Recognition, use the SpeechRecognitionEngine class.

NoteNote

Always call Dispose before you release your last reference to the speech recognizer. Otherwise, the resources it is using will not be freed until the garbage collector calls the recognizer object's Finalize method.

The following example is part of a console application that loads a speech recognition grammar and demonstrates asynchronous emulated input, the associated recognition results, and the associated events raised by the speech recognizer. If Windows Speech Recognition is not running, then starting this application will also start Windows Speech Recognition. If Windows Speech Recognition is in the Sleeping state, then EmulateRecognizeAsync always returns null.

using System;
using System.Speech.Recognition;
using System.Threading;

namespace SharedRecognizer
{
  class Program
  {

    // Indicate whether the asynchronous emulate recognition
    // operation has completed.
    static bool completed;

    static void Main(string[] args)
    {

      // Initialize an instance of the shared recognizer.
      using (SpeechRecognizer recognizer = new SpeechRecognizer())
      {

        // Create and load a sample grammar.
        Grammar testGrammar =
          new Grammar(new GrammarBuilder("testing testing"));
        testGrammar.Name = "Test Grammar";
        recognizer.LoadGrammar(testGrammar);

        // Attach event handlers for recognition events.
        recognizer.SpeechRecognized +=
          new EventHandler<SpeechRecognizedEventArgs>(
            SpeechRecognizedHandler);
        recognizer.EmulateRecognizeCompleted +=
          new EventHandler<EmulateRecognizeCompletedEventArgs>(
            EmulateRecognizeCompletedHandler);

        completed = false;

        // Start asynchronous emulated recognition. 
        // This matches the grammar and generates a SpeechRecognized event.
        recognizer.EmulateRecognizeAsync("testing testing");

        // Wait for the asynchronous operation to complete.
        while (!completed)
        {
          Thread.Sleep(333);
        }

        completed = false;

        // Start asynchronous emulated recognition.
        // This does not match the grammar or generate a SpeechRecognized event.
        recognizer.EmulateRecognizeAsync("testing one two three");

        // Wait for the asynchronous operation to complete.
        while (!completed)
        {
          Thread.Sleep(333);
        }
      }

      Console.WriteLine();
      Console.WriteLine("Press any key to exit...");
      Console.ReadKey();
    }

    // Handle the SpeechRecognized event.
    static void SpeechRecognizedHandler(
      object sender, SpeechRecognizedEventArgs e)
    {
      if (e.Result != null)
      {
        Console.WriteLine("Recognition result = {0}",
          e.Result.Text ?? "<no text>");
      }
      else
      {
        Console.WriteLine("No recognition result");
      }
    }

    // Handle the SpeechRecognizeCompleted event.
    static void EmulateRecognizeCompletedHandler(
      object sender, EmulateRecognizeCompletedEventArgs e)
    {
      if (e.Result == null)
      {
        Console.WriteLine("No result generated.");
      }

      // Indicate the asynchronous operation is complete.
      completed = true;
    }
  }
}

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Show:
© 2014 Microsoft