Изменить громкость на Rear (задних) динамиках

[DllImport("winmm.dll")]
        public static extern int waveOutGetVolume(IntPtr hwo, out uint dwVolume);
 
        [DllImport("winmm.dll")]
        public static extern int waveOutSetVolume(IntPtr hwo, uint dwVolume);
 
        int max_value = 10;
 
        public Form1()
        {
            InitializeComponent();
            // By the default set the volume to 0
            uint CurrVol = 0;
            // At this point, CurrVol gets assigned the volume
            waveOutGetVolume(IntPtr.Zero, out CurrVol);
            //MessageBox.Show(IntPtr.Zero.ToInt32().ToString());
            // Calculate the volume
            ushort CalcVol = (ushort)(CurrVol & 0x0000ffff);
            // Get the volume on a scale of 1 to 10 (to fit the trackbar)
            trackWave.Maximum = max_value;
            trackWave.Value = CalcVol / (ushort.MaxValue / max_value);
        }
 
        private void trackWave_Scroll(object sender, EventArgs e)
        {
            // Calculate the volume that's being set
            int NewVolume = ((ushort.MaxValue / max_value) * trackWave.Value);
            // Set the same volume for both the left and the right channels
            uint NewVolumeAllChannels = (((uint)NewVolume & 0x0000ffff) | ((uint)NewVolume << 16));
            // Set the volume
            waveOutSetVolume(IntPtr.Zero, NewVolumeAllChannels);
        }