Speech Recognition with c#

namespace mypro
{
    public partial class MainWindow : Window
    {
        SpeechRecognitionEngine en = new SpeechRecognitionEngine();

        public MainWindow()
        {
            InitializeComponent();

            en.SetInputToDefaultAudioDevice();

            Choices ch = new Choices("Hello","hey");
            Grammar h = new Grammar(ch.ToGrammarBuilder());
            h.Name = "ha";

   en.LoadGrammarAsync(h);

   en.RecognizeAsync(RecognizeMode.Multiple);

  en.SpeechRecognized += new EventHandler<Speech Recognized EventArgs>(en_SpeechRecognized)
            
        }


public void en_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
        {
            if (e.Result.Grammar.Name == "ha")
            {
                switch (e.Result.Text)
                {
                         
                    case "Hello":
                        Say("hi, may i know your name?");
                         break;
                    case "hey":
                         Say("hi, may i know your name?");
                        break;
                }
            }
        }

    public void Say(string input)
        {
            var s = new SpeechSynthesizer();
            var sa = new Prompt(input);
            s.Speak(sa);
            
        }

       
    }
}