A first-of-its-kind hearing device has been approved that sends vibrations to the brain rather than simply magnifying sound like traditional hearing aids. The surgically implanted device is for adults with moderate to severe nerve hearing loss, not for the profoundly deaf.

Implanted in the skull bone behind the ear, the Vibrant Soundbridge device converts sound into mechanical energy and transfers the energy to the wearer's middle ear via a wire. The energy vibrates delicate structures in the middle ear in much the same way that sound normally would, allowing the brain to interpret the vibrations as sound.

In clinical studies, the Vibrant Soundbridge was shown to improve hearing about as much as conventional hearing aids. On the plus side, the new device was less visible than some standard hearing aids, and it wasn't hampered by earwax and moisture, which can be problematic with conventional devices.

But the surgery to implant the Vibrant Soundbridge entails the usual risks from surgical procedures, including infections and anesthesia risks. Other complications reported by patients in clinical studies included worsened hearing (2 percent), permanently altered taste (2 percent), long-term pain in the ear (5 percent), and a permanent feeling of "fullness" in the ear (16 percent).

FDA approved the implant in August based on a U.S. study of 81 patients, supporting data from European studies, and the recommendation of an FDA advisory committee. The device's manufacturer, Symphonix Devices Inc., San Jose, Calif., is doing an 18-month follow-up study to determine the implant's long-term safety and effectiveness.