Many people have wondered about the screaming you hear when you turn on the power in Kino and how it sounds like there's a monster on the roof. Well I think I just solved it. Check this out. http://www.youtube.com/watch?v=B7b6EkTNOPA&feature=feedu
No, notice how the "screaming" lasts a little longer than his mouth is open, and that it is slowed down. Remember the Shangri-La trailer, how the zombie chick screams the part of the song? Well they obviously just timed that so it looked like she was. Same idea here. I believe it's just a sign/warning that some kind of new monster is coming, because this IS the first map that the NOVA crawlers were introduced.
Just my opinions but I doubt one crawler is going to make that loud of a scream.