How to get the text recognised in variable after "engine.SetInputToWaveFile("D:\record.wav")

Public Class Form1
    Dim engine As New SpeechRecognitionEngine
    Dim gram As Grammar
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
        Dim choices = New Recognition.Choices()
 
        choices.Add("Red")
        choices.Add("Blue")
        choices.Add("Green")
        choices.Add("Yellow")
        Dim gb = New GrammarBuilder()
 
        gb.Append(choices)
 
        Dim doc = New Speech.Recognition.SrgsGrammar.SrgsDocument(gb)
        IO.Directory.CreateDirectory("C:\Test")
        IO.Directory.CreateDirectory("C:\Test\Speech")
        Dim xWriter = System.Xml.XmlWriter.Create("C:\Test\Speech\mygrammar.xml")
 
        doc.WriteSrgs(xWriter)
        xWriter.Close()
 
        Dim compiledFile = New FileStream("C:\Test\Speech\mycompiledgrammar.cfg", FileMode.OpenOrCreate)
 
        Speech.Recognition.SrgsGrammar.SrgsGrammarCompiler.Compile("C:\Test\Speech\mygrammar.xml", compiledFile)
        compiledFile.Close()
 
        gram = New Grammar("C:\Test\Speech\mygrammar.xml")    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If gram IsNot Nothing Then
            engine.LoadGrammar(gram)
            engine.SetInputToWaveFile("D:\record.wav")
        Else
            ' The grammar wasn't loaded...
            ' Do something about the condition or notify the user.
        End If
    End Sub
End Class