Windows 7 has some new audio settings which I haven't been able to control from my C# application. Specifically, within the Input (microphone) properties, there is a Levels Tab containing Microphone and Microphone Boost sliders, and a Microphone mute toggle / checkbox.
I need to programatically ensure that the Microphone is not muted--but have not found the necessary APIs to either read or set the values.
I was unable to find an API that provided control over these specific volume levels. Please add new answers if they are available and I'll gladly accept a working solution.
You can use a very useful library built around windows mixer by Caster Tiu from http://www.codeproject.com/KB/audio-video/AudioLib.aspx?msg=1323850
According to documentation on this page:
Specific controls like Fadder, Microphone Boost, bass, treble, etc. can be accessed via the MixerControl object using ValueAsSigned, ValueAsUnsigned and ValueAsBoolean properties, but they are not implemented as standard properties because they don't belong to all controls.
There is a WalkTreeBackwardsFromPart sample that shows how to enumerate audio endpoints and print out their current volume, You can modify the code to unmute the analog mixer via IDeviceTopology
Windows should unmute the software volume at the beginning of a capture session, does your device have a hardware volume?
The IAudioEndpointVolume interface might work for you. It has functions to get/set mute state and volume levels for a recording or playback device.
Reference: http://msdn.microsoft.com/en-us/library/windows/desktop/dd370892(v=vs.85).aspx
来源：https://stackoverflow.com/questions/8440588/how-can-i-programmatically-control-the-microphone-and-microphone-boost-settings