Rationale and Efficacy of Sound Therapies for Tinnitus and Hyperacusis.

Sound therapies are a common component of treatments for tinnitus and hyperacusis. The original idea was to partially or completely mask tinnitus with broadband noise delivered by sound generators or hearing aids, for a few hours each day. Over several months, many patients reported that their tinnitus became quieter or easier to bear, and that loud sounds became less aversive. However, it wasn't always clear that these benefits could be attributed to sound therapy rather than to other aspects of treatment, such as counseling or hearing aid use, and not all patients reported benefits. During the past few decades, many other sound stimuli have been tried, including narrower bands of noise and tone bursts, music, and nature sounds. These sounds have been filtered in relation to the tinnitus pitch, adjusted for hearing loss, amplitude-modulated, and recently paired with electrical nerve stimulation. Many of our ideas about the neural underpinnings of tinnitus and hyperacusis come from animal models. However, studies of sound treatments in animals with putative tinnitus or hyperacusis have been rare. Clinical sound therapy trials are emerging, but outcomes typically remain modest, and few patients achieve complete remission of tinnitus or hyperacusis, unless the underlying hearing loss is treated with hearing aids or implants, in which case success rates are higher. More studies are needed, on both animal models and human subjects, to further explore the rationales for the various sound therapy options reviewed here, and to optimally tailor sounds and treatment approaches to individual patients, so that maximum benefits can be obtained.