อยากรู้ว่าจะเขียนโปรแกรมสั่งการด้วยเสียงอย่างไรครับด้วย C#

using System.Speech;
using System.Speech.Recognition;

GrammarBuilder grammarBuilder = new GrammarBuilder();
grammarBuilder.Append(new Choices("yee","lob","koon","han","saan","mern","pun","roy","it", "non", "song", "ponlaub", "Some", "si", "Her", "Hold", "Get", "Bat", "Gaow", "Sib", "gee", "booug"));

SpeechRecognitionEngine recognizer = new SpeechRecognitionEngine(); 
recognizer.SetInputToDefaultAudioDevice();
recognizer.UnloadAllGrammars();
recognizer.LoadGrammar(new Grammar(grammarBuilder));
recognizer.SpeechHypothesized += new EventHandler<SpeechHypothesizedEventArgs>(recognizer_SpeechHypothesized);

         private void recognizer_SpeechHypothesized(object sender, SpeechHypothesizedEventArgs e)
         {
                switch (e.Result.Text)
                {
                    case "han":
                        arrCommand.Add("/");
                        break;
                    case "koon":
                        arrCommand.Add("*");
                        break;
                    case "lob":
                        arrCommand.Add("-");
                        break;
                    case "non":
                        arrCommand.Add("1");
                        break;
                    case "it":
                        arrCommand.Add("1");
                        break;
                    case "booug":
                        arrCommand.Add("+");
                        break;
                    case "song":
                        arrCommand.Add("2");
                        break;
                    case "yee":
                        arrCommand.Add("2");
                        break;
                    case "Some":
                        arrCommand.Add("3");
                        break;
                    case "si":
                        arrCommand.Add("4");
                        break;
                    case "Her":
                        arrCommand.Add("5");
                        break;
                    case "Hold":
                        arrCommand.Add("6");
                        break;
                    case "Get":
                        arrCommand.Add("7");
                        break;
                    case "Bat":
                        arrCommand.Add("8");
                        break;
                    case "Gaow":
                        arrCommand.Add("9");
                        break;
                    case "Sib":
                        arrCommand.Add("10");
                        break;
                    case "roy":
                        arrCommand.Add("100");
                        break;
                    case "pun":
                        arrCommand.Add("1000");
                        break;
                    case "mern":
                        arrCommand.Add("10000");
                        break;
                    case "saan":
                        arrCommand.Add("100000");
                        break;
                    default:
                        break;

                }
         }

using System.Speech.Synthesis;

SpeechSynthesizer voice = new SpeechSynthesizer();
voice.SetOutputToDefaultAudioDevice();
voice.Speak("hello world");

 case "one":
                    serialPort.Open ();
                    serialPort.Write("1");
                    serialPort.Close();                    
                    break;
default:
                    voice.Speak("roy pun mern saan");
                    label1.Text = "Default";
                    break;