First, a device of his choosing (a phone playing music, say) generates a varying current--the sound information--and transmits it out a standard 1/8" jack into a cord. Then, that current passes through an amplifier (hence the battery pack) and continues, intensified, up to the coil necklace. Here's where things get interesting. The coil necklace is made from copper magnet wiring. As the current departs the cord and passes through the wiring, in its fluctuating, wave-like form, it is traveling in one of two possible directions: up or down. (A simplified, illustrative example is a sine wave.) Traveling in one direction (i.e. up), it generates a magnetic field that opposes Lee's implanted magnet's field, while the other direction generates an aligning field. When the fields oppose each other, the implanted magnet pushes away from the coil, towards Lee's eardrum. When they align, the implanted magnet pulls towards the coil, away from his eardrum. The coil acts to both intensify and direct the resulting magnetic field. Control the current that passes through the coil, and you are able to control the implanted magnet.