Often, in the middle of the night, Chandler will be snuggled up in the bed between Mark and me. Unfortunately, if one of the cats walks through the room, he will jump up and stomp all over me on his way to chase the offending cat. I don't know how he hears them, they are not audible to the human ear, but I think I have found the answer to the problem in the video below.
I hope the video is still here when you see this, because it is taken off the television (It's Always Sunny in Philadelphia), and You Tube often deletes those.