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SpeechRecognitionEngine.RecognizerUpdateReached Event

Raised when a running SpeechRecognitionEngine pauses to accept modifications.

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

public event EventHandler<RecognizerUpdateReachedEventArgs> RecognizerUpdateReached

Applications must use RequestRecognizerUpdate() to pause a running instance of SpeechRecognitionEngine before modifying its settings or its Grammar objects. The SpeechRecognitionEngine raises this event when it is ready to accept modifications.

For example, while the SpeechRecognitionEngine is paused, you can load, unload, enable, and disable Grammar objects, and modify values for the BabbleTimeout, InitialSilenceTimeout, and EndSilenceTimeout properties. For more information, see the RequestRecognizerUpdate method.

When you create a RecognizerUpdateReached delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

The following example shows a console application that loads and unloads Grammar objects. The application uses the RequestRecognizerUpdate() method to request the speech recognition engine to pause so it can receive an update. The application then loads or unloads a Grammar object.

At each update, a handler for RecognizerUpdateReached event writes the name and status of the currently loaded Grammar objects to the console. As grammars are loaded and unloaded, the application first recognizes the names of farm animals, then the names of farm animals and the names of fruits, then only the names of fruits.

using System;
using Microsoft.Speech.Recognition;
using System.Collections.Generic;
using System.Threading;

namespace SampleRecognition
{
  class Program
  {
    private static SpeechRecognitionEngine recognizer;
    public static void Main(string[] args)
    {

      // Initialize a SpeechRecognitionEngine object and configure its input.
      using (recognizer = new SpeechRecognitionEngine(new System.Globalization.CultureInfo("en-US")))
      {
        recognizer.SetInputToDefaultAudioDevice();

        // Create the first grammar - Farm.
        Choices animals = new Choices(new string[] { "cow", "pig", "goat" });
        GrammarBuilder farm = new GrammarBuilder(animals);
        Grammar farmAnimals = new Grammar(farm);
        farmAnimals.Name = "Farm";

        // Create the second grammar - Fruit.
        Choices fruit = new Choices(new string[] { "apples", "peaches", "oranges" });
        GrammarBuilder favorite = new GrammarBuilder(fruit);
        Grammar favoriteFruit = new Grammar(favorite);
        favoriteFruit.Name = "Fruit";

        // Attach event handlers.
        recognizer.SpeechRecognized +=
          new EventHandler<SpeechRecognizedEventArgs>(recognizer_SpeechRecognized);
        recognizer.RecognizerUpdateReached +=
          new EventHandler<RecognizerUpdateReachedEventArgs>(recognizer_RecognizerUpdateReached);
        recognizer.SpeechRecognitionRejected +=
          new EventHandler<SpeechRecognitionRejectedEventArgs>(recognizer_SpeechRecognitionRejected);

        // Load the Farm grammar.
        recognizer.LoadGrammar(farmAnimals);

        // Start asynchronous, continuous recognition.
        recognizer.RecognizeAsync(RecognizeMode.Multiple);
        Console.WriteLine("Starting asynchronous, continuous recognition");
        Console.WriteLine("  Farm grammar is loaded and enabled.");

        // Pause to recognize farm animals.
        Thread.Sleep(7000);
        Console.WriteLine();

        // Request an update and load the Fruit grammar.
        recognizer.RequestRecognizerUpdate();
        recognizer.LoadGrammarAsync(favoriteFruit);
        Thread.Sleep(7000);

        // Request an update and unload the Farm grammar.
        recognizer.RequestRecognizerUpdate();
        recognizer.UnloadGrammar(farmAnimals);
        Thread.Sleep(7000);
      }

      // Keep the console window open.
      Console.WriteLine();
      Console.WriteLine("Press any key to exit...");
      Console.ReadKey();
    }

    // At the update, get the names and enabled status of the currently loaded grammars.
    public static void recognizer_RecognizerUpdateReached(
      object sender, RecognizerUpdateReachedEventArgs e)
    {
      Console.WriteLine();
      Console.WriteLine("Update reached:");
      Thread.Sleep(1000);

      string qualifier;
      List<Grammar> grammars = new List<Grammar>(recognizer.Grammars);
      foreach (Grammar g in grammars)
      {
        qualifier = (g.Enabled) ? "enabled" : "disabled";
        Console.WriteLine("  {0} grammar is loaded and {1}.",
        g.Name, qualifier);
      }
    }

    // Write the text of the recognized phrase to the console.
    static void recognizer_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
    {
      Console.WriteLine("    Speech recognized: " + e.Result.Text);
    }

    // Write a message to the console when recognition fails.
    static void recognizer_SpeechRecognitionRejected(object sender, SpeechRecognitionRejectedEventArgs e)
    {
      Console.WriteLine("    Recognition attempt failed");
    }
  }
}

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