Strange Monster noises

[Krohm]

I look at it as sort of the audio equivalent of fear or an adrenaline rush. Like you're hearing the fear that Daniel feels when he's been spotted.

I also think it's main purpose is to let you know you're about to be chased, but I can't think of what else that sound would be. It doesn't seem to get louder or softer depending on how close a grunt or brute is from what I remember, so I don't think it comes from them.