Probably. I use push to talk, so it isn't a huge deal if it does. In any case, no one has ever complained about it...
I have Teamspeak running via my headphones, and all other sounds running through the speakers, games, music, movies etc,
my Mic is on Voice Activation ( purely because for some reason my TS windows has be be the 'active window' on vista or the button i assign to 'push to talk' does nothing :/ )
but the only 'complaints' i receive are breathing, or singing and forgeting the mic is on...
The other facter Birdy, is how close / far your mic is from your mouth, and how responsive it is, can you per say set the voice activation and have the mic comfortable above your nose ? not hear anything other than when you speak ?
also, im sitting about 60CM away from my 3 desk satelite speakers, and the subs under the desk, i can quite happily have my music blasting out as loud as i like without any pick up from my mic, How close are you to your speakers ?