http://bugs.winehq.org/show_bug.cgi?id=5159
--- Comment #61 from Brandon Howard FinalCrisisSX@Hotmail.com 2011-04-14 11:43:53 CDT --- I don't know what I did otherwise, but after tinkering with the sound some more and once again decreasing my mic volume to 45% or so, people say my mic is a little low (naturally) but no longer sounds horrible or breaks their sound in-game. The self-test sounds exactly the same no matter what recording volume is apparently, which is to say: scratchy and awful.. I'm guessing it does some kind of gain control in the self-test that works differently than the actual in-game chat for whatever reason. However, I had a friend send me a demo of myself talking in game, and it sounded just fine there minus some minor buzz which happens in windows too iirc (also after turning the recording volume and other settings way down or off, as mentioned elsewhere on the net).
So.. consider my previous comments on this page void and probably unrelated to wine, I suppose. Tf2 probably just does a lousy job of managing voice volumes compared to any other recording programs used.