An implantable hearing aid aims to overcome the drawbacks of traditional hearing aids--they're inconvenient, they're unsightly, and they're not supposed to get wet. The device, being developed by Otologics of Boulder, CO, uses a microphone implanted underneath the skin to pick up sound.

The signal from the microphone is processed and sent to a vibrating piston implanted against small bones of the middle ear, which transmit the vibrations to the inner ear. The user recharges the device's battery by placing a small radio transmitter against his or her head. In an early clinical trial, subjects using the device did not hear quite as well as they did with traditional hearing aids. The question is whether patients will see reduced performance--as well as the higher cost and surgical risk--as a tolerable price to pay for convenience and cosmetic benefits.