Originally posted by Fish:

its ambient sounds don't worry if you think you missed a room try to use your pickax on the floor and crouch (Going stealth mode) if you see the eye half open that means you missed a room, if you see its closed that means you cleared the crypt.

So don't worry its just ambient sounds the more you play the more you will recognize what is true and what is false.

The crypts don't have ambient dragur sounds. That does happen a lot, but this specific one - no.