Disturbances of loudness perception.

This article reviews information on some auditory disorders that have in common a disturbance in loudness perception. The perceptual disturbances in these disorders have interchangeably been labeled "hyperacusis," "dysacusis," or "phonophobia." Our question concerns whether the loudness disturbances associated with these auditory disorders are sufficiently different as not to justify the equivalence implied by the labelling. Emphasis is placed on those articles that have given clear accounts of the phenomenology of the disturbed perceptual experience and have offered testable hypotheses about the mechanisms underlying it. Hypotheses about the origins of disturbed loudness perception are compared with independent experimental and clinical evidence on those mechanisms. The disturbances of loudness perception that occur in cochlear hearing loss, facial nerve paralysis and stapedectomy, and in more "central" disorders are phenomenologically different, have different underlying mechanisms, and merit different labels that most of them do not currently receive.