Inspired by the ghost story "The Raven" by Edgar Allan Poe. Fantastic spook story, I recommend everyone to read it! Here's a link: http://www.heise.de/ix/raven/Literature/Lore/TheRaven.html This is my interpretation of the strange tapping noise heard in the story. Maybe it's the lost Lenore? Or did the raven create the sound? The question is open for speculation.