currently, it looks like incoming voice chat is automatically set to 80-90% if you happen to go into options and look at the individual players. a majority of the time, people are too quiet and the extra boost i can put on them isn't enough. i even backed down the game sounds to try to hear them.
here's an idea. give us a range from 50% to 150% or 0% to 200% with the default being 100%. it'll give us more flexibility to boost the mumblers and squelch the loud folks.
outgoing voice chat by default is 100%, but apparently, most folks don't realize that windows has it's own mic recording volume. i would suggest hooking the mic volume to the windows recording volume if possible, making changes in the game change the windows recording volume.
also, a way to test out the microphone in the options menu wouldn't hurt. or perhaps an auto-configuration: hit a button, say a few things and the game automatically sets your outgoing to a more proper volume.