The sound appears to be audible at at least two frequencies. The most pronounced is between 1199 Hz and 1226 Hz. The less distinct is at about 378 Hz. I believe the second may just be low frequency noise in the recording, but I've isolated those two frequencies and while, as I said, some of it sounds like LF noise, the higher one (1199 to 1226 Hz) definitely sounds (to my ear at least) like something that's actually there. It's a very haunting, breathy sound. Almost like a long, deep vocal note being held in a monastic style or something.
I don't know of a better way to upload the audio, so here it is while it lasts. Again, this is pretty crude. I just did it by ear and with free software:
Note: I edited out as much of the talking and clicks/movement noises as I could.
edit on 1/26/2012 by AceWombat04 because: Added info