Did you hear that? Something was activated in the vase room

I was re-watching the scene in Prometheus last night where the crew enters the the room with all the vases. When they show the foot stepping on the soil and revealing worms, there is a noise like maybe they stepped on some sort of trigger/locking mechanism.  Has anyone else heard this?  What do you think it was?

If you listen you'll hear what sounds like a vault door opening.