Headset making beeping sound.

Hello.
I've recently bought a turtle beach px21 headset to use on my xbox 360, because my old one, a turtle beach x12, didn't work properly anymore. I was also hoping the px21 would have a better microphone. This is, sadly, not the case.

When I talk, there is a beeping noise in the background. I have no idea what causes it. I asked around on turtle beach's site, but they didn't help alot either.

Does anyone know what is causing this? I have tried using the microphone on a different xbox 360 controller, and it's still the same. I recorded my voice on the computer and it was crystal clear. What the heck?