Audio output is quiet, doesn't respond to volume slider.

[nicholus.h]

I installed Mumble and it's mostly working, but it's kind of quiet and is completely drowned out by the game audio. I've tried adjusting the volume slider in the "audio output" section of the settings, but it is literally the same volume whether it is set to 0% or 200%. This even happens when I'm testing it not in game. I uninstalled and reinstalled but it still happens and I can't figure out what's going on.

Is this a common problem? Is there something I can do to fix it?

Thanks.