How to covert Audio file to word file in vb.net 2010?

Dim sre As New SpeechRecognitionEngine()
Dim gr As Grammar = New DictationGrammar()
sre.LoadGrammar(gr)
sre.SetInputToWaveFile("YourWavFileLocation") 'you must give full path 
sre.BabbleTimeout = New TimeSpan(Int32.MaxValue)
sre.InitialSilenceTimeout = New TimeSpan(Int32.MaxValue)
sre.EndSilenceTimeout = New TimeSpan(100000000)
sre.EndSilenceTimeoutAmbiguous = New TimeSpan(100000000)

Dim sb As New StringBuilder()
While True
    Try
        Dim recText = sre.Recognize()
        If recText Is Nothing Then
            Exit Try
        End If

        sb.Append(recText.Text)
    Catch ex As Exception
        'handle exception
        'give msgbox about error or etc
    End Try
End While
Return sb.ToString()