People can hear my music/game sounds when using vent even when my microphone is NOT

[MRMEPHiST0]

connected.? Whenever I press on my vent speak button or while I am using skype people can hear the sounds coming from my computer even when my microphone is not connected to the tower, I don't know how to stop this and I have tried to tool around with the sound settings and I have updated my drivers for all things audio. I have noticed i get the most sound feeding through on iTunes but it still happens if i have any other sound playing on my computer.