This piece of retainer-like jewelry is the creation of Aisen Chacin, a student at Parsons School of Design in New York. It differs in one very important way from the standard rapper’s grill: it includes a motor hooked up to the headphone jack of an iPod that lies flush against the wearer’s palate. To play your tunes, you manipulate the iPod’s controls with your tongue, and, thanks to the pulsing of the motor against your teeth, you can hear the music.

This  phenomenon  is known as bone conduction , which allows sound to be transmitted to your hearing apparatus by the vibration of bones rather than the vibration of air hitting your ear drum. It’s why your voice on a recording sounds different than the voice you hear when you speak, and it’s the basis of certain hearing aids, as well as some headsets worn by divers so they can receive messages from people out of the water.

Users of Chacin’s grill probably hear low notes especially loudly, because bone conducts lower frequencies better than air does. Basically, your skull is a built-in subwoofer.

Source:discovermagazine.com