I've heard of the lost cosmonauts before. But what is the first sound? I haven't listened to all of it yet, mainly because you grouped it with the lost cosmonauts, and those recordings scare the hell out of me as well, even though I believe they are mostly hoaxes.
It's certainly not hard to guess why unknown sounds would trigger fear in humans from an evolutionary standpoint. Biologically I wouldn't care to speculate.
The first sound is a (german) numbers station where a woman (i can't help my self and interpret the voice as a child's voice) speaks some testing numbers (i guess) it's 1,2,3,4,5,6,7,8,9,0 - the interleave signal is: http://en.wikipedia.org/wiki/Swedish_Rhapsody_No._1
It's certainly not hard to guess why unknown sounds would trigger fear in humans from an evolutionary standpoint. Biologically I wouldn't care to speculate.