先在C盤下找到sapi.dll文件，添加的引用

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using SpeechLib;

namespace WindowsApplication1
...{
    public partial class Form1 : Form
    ...{
        public Form1()
        ...{
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        ...{
            try
            ...{
                SpeechVoiceSpeakFlags spFlags = SpeechVoiceSpeakFlags.SVSFlagsAsync;
                SpVoice voice = new SpVoice();
                if (this.richTextBox1.Text.Trim() == string.Empty)
                ...{
                    voice.Speak("請輸入數據！", spFlags);
                }
                else
                ...{
                    voice.Speak(this.richTextBox1.Text, spFlags);
                }
            }
            catch (Exception Err)
            ...{
                MessageBox.Show(Err.Message);
            }
        }
    }
}