how to convert speech to text using c#

RaisKazi it's not working i already tried this please post complete code...

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Speech;
using System.Speech.Synthesis;
using System.Speech.Recognition;
using System.Speech.Recognition.SrgsGrammar;
using System.Threading;


namespace SpeechToText
{
public partial class Form1 : Form
{
SpeechSynthesizer sSynth = new SpeechSynthesizer();
PromptBuilder pBuilder = new PromptBuilder();
SpeechRecognitionEngine sRecognize = new SpeechRecognitionEngine();

public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
pBuilder.ClearContent();
pBuilder.AppendText(textBox1.Text);
sSynth.Speak(pBuilder);
}

private void button2_Click(object sender, EventArgs e)
{
button2.Enabled = false;
button3.Enabled= true;
Choices sList = new Choices();
sList.Add(new string[] { "hello","hi","how","are","you","srinivas","test","i"});
Grammar gr = new Grammar(new GrammarBuilder(sList));
try
{
sRecognize.RequestRecognizerUpdate();
sRecognize.LoadGrammar(gr);
sRecognize.SpeechRecognized += sRecognize_SpeechRecognized;

sRecognize.SetInputToDefaultAudioDevice();
sRecognize.RecognizeAsync(RecognizeMode.Multiple);

}
catch
{
return;
}
/* sRecognize.SetInputToDefaultAudioDevice();
sRecognize.LoadGrammar(new DictationGrammar());
sRecognize.SpeechRecognized += new EventHandler<speechrecognizedeventargs>(sRecognize_SpeechRecognized);
sRecognize.RecognizeAsync(RecognizeMode.Multiple);*/

}

void sRecognize_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
{
/* foreach (RecognizedWordUnit word in e.Result.Words)
{
listBox1.Items.Add(word.Text);
}*/
if (e.Result.Text == "exit")
{
Application.Exit();
}
else
{
textBox1.Text = textBox1.Text + " " + e.Result.ToString();
}
}



private void Form1_Load(object sender, EventArgs e)
{
// sRecognize.SpeechRecognized += new EventHandler<speechrecognizedeventargs>(sRecognize_SpeechRecognized);

}



}
}
this is my code but speech is not recogniging...can u help me...