NAudio是成熟、开源的C#音频开发工具，它包含录音、播放录音、格式转换、混音调整等功能。

      NAudio 开源地址：  https://github.com/naudio/NAudio

      本文是设置获取系统扬声器的音量，获取麦克风的音量见地址：https://blog.csdn.net/zsz139/article/details/106228910

       1、获取当前系统扬声器音量       

private int GetCurrentSpeakerVolume()
{
    int volume = 0;
    var enumerator = new MMDeviceEnumerator();

    //获取音频输出设备
    IEnumerable<MMDevice> speakDevices = enumerator.EnumerateAudioEndPoints(DataFlow.Render, DeviceState.Active).ToArray();
    if (speakDevices.Count() > 0)
    {
        MMDevice mMDevice = speakDevices.ToList()[0];
        volume = Convert.ToInt16(mMDevice.AudioEndpointVolume.MasterVolumeLevelScalar * 100);
    }
    return volume;
}

       2、设置当前系统麦克风音量 volume 取值 0-100

private void GetCurrentSpeakerVolume(int volume)
{
    var enumerator = new MMDeviceEnumerator();
    IEnumerable<MMDevice> speakDevices = enumerator.EnumerateAudioEndPoints(DataFlow.Render, DeviceState.Active).ToArray();
    if (speakDevices.Count() > 0)
    {
        
        MMDevice mMDevice = speakDevices.ToList()[0];
        mMDevice.AudioEndpointVolume.MasterVolumeLevelScalar = volume / 100.0f;
    }
}