How do I convert my speech to text?

Using System.Speech

public class MyRecognizer {
    public string ReadAudio() {
        SpeechRecognitionEngine sre = new SpeechRecognitionEngine();
        Grammar gr = new DictationGrammar();
        sre.LoadGrammar(gr);
        sre.SetInputToWaveFile("C:User\\Audio.wav");
        sre.BabbleTimeout = new TimeSpan(Int32.MaxValue);
        sre.InitialSilenceTimeout = new TimeSpan(Int32.MaxValue);
        sre.EndSilenceTimeout = new TimeSpan(100000000);
        sre.EndSilenceTimeoutAmbiguous = new TimeSpan(100000000); 

        StringBuilder sb = new StringBuilder();
        while (true)
        {
           try
           {
              var recText = sre.Recognize();
              if (recText == null)
              {               
                 break;
              }
              sb.Append(recText.Text);
           }
           catch (Exception ex)
           {   
               //handle exception      
               //...
               break;
           }
        }
        return sb.ToString();
     }
}