public FrmVoice()
        {
            InitializeComponent();
        }

        [DllImport("user32.dll", EntryPoint = "SendMessageA")]
        public static extern int SendMessage(IntPtr handle, int wMsg, int wParam, int lParam);

        private const int WM_APPCOMMAND = 0x319;
        private const int APPCOMMAND_VOLUME_UP = 10;
        private const int APPCOMMAND_VOLUME_DOWN = 9;
        private const int APPCOMMAND_VOLUME_MUTE = 8;

        private void buttonVoiceUp_Click(object sender, EventArgs e)
        {
            SendMessage(Handle, WM_APPCOMMAND, 0x30292, APPCOMMAND_VOLUME_UP * 0x10000);
        }

        private void buttonVoiceDown_Click(object sender, EventArgs e)
        {
            SendMessage(Handle, WM_APPCOMMAND, 0x30292, APPCOMMAND_VOLUME_DOWN * 0x10000);
        }

        private void buttonMute_Click(object sender, EventArgs e)
        {
            SendMessage(Handle, WM_APPCOMMAND, 0x200EB0, APPCOMMAND_VOLUME_MUTE * 0x10000);
        }


        protected override void WndProc(ref Message m)//监视Windows消息
        {
            const int WM_APPCOMMAND = 0x319;

            switch (m.Msg)
            {
                //case WM_APPCOMMAND:
                //    {
                //        MessageBox.Show(m.ToString());
                //    }
                //    break;
            }

            base.WndProc(ref m); //将系统消息传递自父类的WndProc
        }