That's a pretty interesting approach.

I experienced audio hypnogogia a few nights ago and found it easy to concentrate on the sounds and voices as they occurred. The only problem is that I equate hearing voices to being crazy, and although I knew I was just falling asleep it still felt uncomfortable and a little frightening.

I'm going to give this a shot tonight though, because I was using visual hypnogogia techniques at the time but it seemed to be the audio and sounds that really pulled me in.