private async void InitDefaultRecognizerAsync()
{
if (!_recognizerInitialized)
{
var webSearchGrammar = new Windows.Media.SpeechRecognition.SpeechRecognitionTopicConstraint(Windows.Media.SpeechRecognition.SpeechRecognitionScenario.WebSearch, "webSearch");
Recognizer.Constraints.Add(webSearchGrammar);
await Recognizer.CompileConstraintsAsync();
_recognizerInitialized = true;
}
}