This was driving me crazy at first, when I had the transmitter connected to the 1st stage and it was right behind my head. The sound is VERY short range. If I tilted my head forward or put chin to chest, I could BARELY hear it, but if my head was in normal position it was very loud and irritating.
I solved it by adding a foot or so of hose, so now the transmitter runs down the inside of my BCD and hangs out tucked near my side. Can't hear it at all anymore.
