Basically, I'm concerned that if I use a microphone---or, the microphone function on a headset---the speaker-sound will feed back in to the microphone as well.
Use case: playing computer games with friends. I want to communicate with voice, but I'd also like to get the immersive experience of my 5.1 speaker system. Music or sound effects will constantly be going on in the game, and I don't want to transmit those over the microphone---just my voice. Also important, when my friends' voices come out of the speakers, I don't want to transmit those either.
So, do microphones these days do some kind of background-noise cancellation? Would a headset work better? (And if so, can I use it for only the voice function?) What about a Bluetooth thingy; would one of the products made for cell phones be good at noise cancellation?