Turn up the volume and listen very, very closely to the very end of this track. You'll hear something like a human voice.
http://www.youtube.com/watch?v=aZxgCeReCsg
Then I extracted the strange sound.
http://www.youtube.com/watch?v=s7PcS-0yOhw
As you can hear, it really was a human voice! I can catch a Japanese sentence "Oi, machigai!" which means "Hey, mistake!"
My guess is that someone at the recording, maybe the recording engineer, accidentally let out his voice to point out someone's mistake and one of the microphones caught it. Anyway, it sounds really creepy.
