Stub your toe, stumble over, break your wrist, and become even more scared than you already are. You tend to hear sounds more and more because your body is desperate to understand where it is and where to go. But, because you can't see the source of the sound, the mind makes educated guesses. And, more often than not that guess will be determined by your current state of mind. When we are scared, the default setting for any noise is something we are scared of. Maybe this is just our imagination or maybe it is legitimate.