C# - Spracherkennung

private SpeechRecognitionEngine recognizer = new SpeechRecognitionEngine();

//--------Beim laden aufrufen----------
recognizer.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(recognizer_SpeechRecognized);
Grammar grammar = new Grammar("grammar.xml", "Befehle");
recognizer.UnloadAllGrammars();
recognizer.LoadGrammar(grammar);
//--------------------------------------

private void btnListen_Click(object sender, EventArgs e) {
   recognizer.SetInputToDefaultAudioDevice();
   recognizer.RecognizeAsync(RecognizeMode.Multiple);
}

private void btnStop_Click(object sender, EventArgs e) {
   recognizer.RecognizeAsyncCancel();
}

[DllImport("user32.dll")]
public static extern void LockWorkStation();

private void recognizer_SpeechRecognized(object sender, SpeechRecognizedEventArgs e) {
   if (e.Result.Text == "Schließen") {
      recognizer.Dispose();
      this.Close();
   } else if (e.Result.Text == "Sperren") {
      LockWorkStation();
   }
}



-----------------XML-Datei-------------------
<grammar xmlns="http://www.w3.org/2001/06/grammar"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://www.w3.org/2001/06/grammar
                             http://www.w3.org/TR/speech-grammar/grammar.xsd"
         xml:lang="de-DE" version="1.0">
  <rule id="Befehle" scope="public">
    <one-of>
      <item>Schließen</item>
      <item>Sperren</item>
    </one-of>
  </rule>
</grammar>