I think I posted this several months ago so I figured it was time to get excited and nerdy about it again. This is a really amazing auditory illusion. They are like optical illusions but, instead, your mind is tricked in to thinking it is hearing something when, in fact, it is not.
For this to work you will need to use headphones.
Here is an explination:
This is a demonstration of the stereo effect. Listening to it, you feel as though you are in a barber’s chair, with the barber moving around you, clipping away at your hair. As the barber “moves” to your right, the volume increases slightly in the right channel and decreases in the left. Similarly, increases in the volume of sound from the clippers give the impression that he is bringing them closer and closer to each ear. The illusion demonstrates our ability to locate sounds in space; by comparing the inputs to the two ears, we can work out where a sound is coming from.