If you can find a way to route your chat program's audio through another program you can try running it through a software limiter or compressor (like a VST or Direct-X plugin on windows), that should take care of the problem.

If you're feeling adventureous, try compiling my Audio::LADSPA modules and the CMT library . That should give you (amongst other things) a software compressor and audio out , now all you need is a way to route your chat program's audio into it. If you get it to work, let me know.

Good luck,
Joost.