Abstract:

Limited but convincing evidence suggests neural plasticity plays a role in the development and maintenance of tinnitus. Tinnitus is generally pitch matched with high frequencies (<6kHz) and is often associated with very hearing loss, although the conventional audiometric thresholds may be normal or near normal. It is hypothesized that the brain experiences high-frequency air conduction auditory deprivation and this is a causative factor in tinnitus. If the low-pass middle ear is circumvented by bone conduction stimulation, residual high-frequency receptors in the cochlea can again be activated. High-frequency bone conduction transducers were fabricated to deliver frequencies from 6 to 40 kHz. The transducers were aluminum ceramic bimorphs with circular topology which were heavily damped by mass loading to the mastoid with resonances at 9 and 39 kHz. Ten subjects with persistent tinnitus were selected to listen to proprietary high-frequency patterned stimulation for two half-hour sessions for 4 weeks. Exit questionnaires revealed satisfaction with tinnitus relief in the majority (60%) with residual inhibition lasting on the order of weeks (mean=1.5 weeks). Encouraged by these findings, more extensive trials are underway to explore the efficacy of high-frequency bone conduction treatment in central tinnitus.