Everyone I ran into is having this problem including myself. The push to talk feature even when turned on constantly picks up your voice even without you holding the key. Sometimes even when we have never pushed the talk key we will hear our voice and it constantly gives us away and made a lot of games really awkward.
Also on a side note it would be really nice to have a push to talk button on the controller somehow because talking in game is extremely tedious and hard to do when your a controller user and have to take one hand off to go and hold the T key.