Recognizing Speech Using the Dictation and Web Search Grammars

The SpeechRecognizerUI uses the online dictation grammar by default if no grammar is added to its grammar set. In the following example, a SpeechRecognizerUI is created and its speech recognizer’s RecognizeAsync method is called. The speech recognizer returns the recognized text in Result property of the SpeechRecognitionResult object, as shown:

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SpeechRecognizerUI recognizerUI = new SpeechRecognizerUI();

SpeechRecognitionResult result;

try
{
    result = await recognizerUI.Recognizer.RecognizeAsync();
}
catch (Exception ex)
{
    // Handle unable to recognize speech...
    return;
}

string recognizedText = result.Text;
...

You can explicitly add the dictation, or a web search grammar, to a grammar set using the SpeechGrammarSet.AddGrammarFromPredefinedType, as shown:

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SpeechRecognizerUI recognizerUI = new SpeechRecognizerUI();
recognizerUI.Recognizer.Grammars.AddGrammarFromPredefinedType(
    "WebSearch", SpeechPredefinedGrammar.WebSearch);

Unlike the dictation grammar, which is loaded by default, the web search grammar must be added to a speech recognizer’s grammar set before starting recognition.