[Hyperacusis, phonophobia, and recruitment. Abnormal deviations of hearing associated with hypersensitivity to sound]

Abstract

Hypersensitivity to sound is a common description of distinct nosological phenomena of peripheral and central hearing disorders, which are characterized by intense suffering from the acoustic environment. One can distinguish between recruitment accompanying inner ear hearing loss, hyperacusis with a general hypersensitivity to sound of any frequency, and phonophobia as an anxious sensitivity towards specific sound largely independent of its volume. While recruitment can be described as a peripheral reaction caused by a lack of outer hair cell moderation, hyperacusis and phonophobia represent disturbances of central auditory processing without peripheral pathology, often combined with psychosomatic reactions. Due to insufficient efferent inhibition, hyperacusis often follows psychovegetative exhaustion. In cases of phonophobia, peripheral and efferent hearing functions are usually intact, but certain learning (conditioning) processes lead to development of specific reactions and avoidance patterns to certain content-related acoustic stimuli. This article describes those different phenomena with regard to their clinical appearance, diagnostics, and possibilities for therapy.