SpeechRecognitionEngine Class

You can create an instance of this class for any of the installed speech recognizers. To get information about which recognizers are installed, use the static InstalledRecognizers() method.

This class is for running speech recognition engines in-process, and provides control over various aspects of speech recognition, as follows:

• To create an in-process speech recognizer, use one of the SpeechRecognitionEngine constructors.

• To manage speech recognition grammars, use the LoadGrammar, LoadGrammarAsync, UnloadGrammar, and UnloadAllGrammars methods, and the Grammars property.

• To configure the input to the recognizer, use the SetInputToAudioStream, SetInputToDefaultAudioDevice, SetInputToNull, SetInputToWaveFile, or SetInputToWaveStream method.

• To perform speech recognition, use the Recognize or RecognizeAsync method.

• To modify how recognition handles silence or unexpected input, use the BabbleTimeout, InitialSilenceTimeout, EndSilenceTimeout, and EndSilenceTimeoutAmbiguous properties.

• To change the number of alternates the recognizer returns, use the MaxAlternates property. The recognizer returns recognition results in a RecognitionResult object.

• To synchronize changes to the recognizer, use the RequestRecognizerUpdate method. The recognizer uses more than one thread to perform tasks.

• To emulate input to the recognizer, use the EmulateRecognize and EmulateRecognizeAsync methods.

The SpeechRecognitionEngine object is for the sole use of the process that instantiated the object. By contrast, the SpeechRecognizer shares a single recognizer with any application that wants to use it.

Note
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 shows part of a console application that demonstrates basic speech recognition. Because this example uses the Multiple mode of the RecognizeAsync(RecognizeMode) method, it performs recognition until you close the console window or stop debugging.

using System;
using System.Speech.Recognition;

namespace SpeechRecognitionApp
{
  class Program
  {
    static void Main(string[] args)
    {

      // Create an in-process speech recognizer for the en-US locale.
      using (
      SpeechRecognitionEngine recognizer =
        new SpeechRecognitionEngine(
          new System.Globalization.CultureInfo("en-US")))
      {

        // Create and load a dictation grammar.
        recognizer.LoadGrammar(new DictationGrammar());

        // Add a handler for the speech recognized event.
        recognizer.SpeechRecognized += 
          new EventHandler<SpeechRecognizedEventArgs>(recognizer_SpeechRecognized);

        // Configure input to the speech recognizer.
        recognizer.SetInputToDefaultAudioDevice();

        // Start asynchronous, continuous speech recognition.
        recognizer.RecognizeAsync(RecognizeMode.Multiple);

        // Keep the console window open.
        while (true)
        {
          Console.ReadLine();
        }
      }
    }

    // Handle the SpeechRecognized event.
    static void recognizer_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
    {
      Console.WriteLine("Recognized text: " + e.Result.Text);
    }
  }
}

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference