Ever heard of SVC? It stands for Software Voice Changer. I bought it a few months ago for a halloween project. The software filters ALL sounds from any program at any time in full duplex. However, I can't figure out how they did it. I too am trying to figure this out for my own reasons. However, it might be possible to tap into the mixer from C++ or VB. I'm working on that. But so far no luck. If you tap into the mixer, you can have all sound run through your software.