LASTING relief may be at hand for the world's one billion tinnitus sufferers. To cancel out the maddening ringing, a company in New Jersey has invented a device that makes a bone behind the ear vibrate.
The Aurex-3, developed by ADM Tronics in New Jersey, works by pressing a small vibrating probe onto the mastoid bone behind the ear. The cochlea-the coiled part of the inner ear that turns mechanical vibrations into neural impulses-is housed within this bone, and the vibrations are effectively applied directly to it.
Initially, the user tunes the frequency of the probe by adjusting a slider on a portable control box until the sound stops. This con-firms that they have matched the frequency of the ringing with that of the probe. Once the frequencies match, the Aurex-3 takes over and works out a complex harmonic tone based around this frequency. "It's called beat harmonics," explains André Di Mino, whose father developed the Aurex-3 to cure his own tinnitus. "When the frequency hits a specific harmonic, which is the opposite sine wave of the tone that the person is hearing, it cancels out the sounds."
This technique, called masking, is already used in other devices that give tinnitus sufferers short-term relief. Di Mino believes the Aurex-3 takes masking further by offering long-term benefits without interfering with hearing. He claims the harmonic helps mop up all the residual noises, not just the main ringing or roar.
Other masking devices fit into the ear canal and often use white noise to blank out sounds. Because they fit inside the ear they can impair ordinary hearing.
Author: Duncan Graham-Rowe
New Scientist issue 8th August 1998, page 6
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