Hyperacusis

Hyperacusis is an increased sensitivity to sound and a low tolerance for environmental noise. Definitions of hyperacusis can vary significantly; it often revolves around damage to or dysfunction of the stapes bone, stapedius muscle or tensor tympani. It is often categorized into four subtypes: loudness, pain (also called noxacusis), annoyance, and fear. It can be a highly debilitating hearing disorder.

There are a variety of causes and risk factors, with the most common being exposure to loud noise. It is often coincident with tinnitus. Proposed mechanisms in the literature involve dysfunction in the brain, inner ear, or middle ear.

Little is known about the prevalence of hyperacusis, in part due to the degree of variation in the term's definition. Reported prevalence estimates vary widely, and further research is needed to obtain strong epidemiological data.