I wasn't sure if any of that 'music' was actually played in the film clip. Unfortunately, from the way it was described, I guess it might have been the effect of two sine waves getting mixed - but that was a common sound back in the late sixties because all commercial radios were analog, so why would it excite the astronauts so much.
I think another question here is just why NASA felt the need to censor bits of information from these missions - it is as though they expected some weird things to happen.
David