Windows 7 Soundcard Control

ABB developer

New Member
I'm building an audio app in Labview that needs to loop the microphone out to the speaker at times. The checkbox control is in the Control Panel/Sound/Microphone dialog. I can control the volume through user32.dll although the example I found uses 3 hex constants for parameters and I have no idea where they came from. I've searched the windows api docs but really can't find what I need. How would I control this through my code and where can I find this documentation?