I have a flightline 760 radio / intercom. It is a nice little unit and for the money I have been very pleased with it. Unlike most other radios I have used the VOX / squelch sensitivity is a setting you have to go in and change between 4 set points (HI-LO), not a dial. I wear a Bose A20 headset and the only time the VOX activates is when I talk, same thing with a standard DC headset I have been borrowing to use for passengers (just got into phase 2). I picked up a cheapo GCA - 4G headset so I don't have to keep borrowing the David Clarks and the only way I can keep them from activating the VOX is to clamp my finger over the mic. I even have an extra muff over the mic. Any tips or tricks here? I kind of thought all mic's were more or less created equal in this regard. Is there something I could wire into the passenger mic (like a reostat) to manually adjust the VOX sensitivity? I suppose I could go out and spend 3 times as much for a DC headset or 10 times as much for BOSE but I'd prefer not to. on a related not - all of these aviation headsets seem to have an opening for the the mic on the front (mouth side) and back (panel side) why is that? does one cancel out the other? If not why do they put a mic (which is clearly going to be used in a relatively noisy environment) away from the users mouth?