Auditory Illusions Watch
They are pretty cool.
"These are called Holophonic sounds and are made to be listened to with headphones. They are recorded with a dummy head that has two microphones, one in each ear. The shape of the head and ears must be similar to a human head."
Especially the knocking!
"Meanwhile I will go over here and play the music. That is what I do here at the barber shop."