On the Etiology of Listening Difficulties in Noise Despite Clinically Normal Audiograms.

This is a narrative review, so the author selects studies and no systematic search or quality appraisal is described. Many mechanistic findings come from animals, and the link to human listening difficulties is not proven. The paper notes that APD test failures may be misleading when central lesions are rare. Clinical tests for hidden hearing loss, nerve synapse damage, and spatial processing are described as promising, not established. Evidence for auditory training comes from small or single studies, so it cannot be treated as a proven treatment for all listening difficulties.

Do not conclude that a normal audiogram proves the ear and auditory nerve are intact, or that poor speech-in-noise performance proves central auditory processing disorder. The review states that hidden peripheral loss, binaural processing deficits, language problems, and attention problems can all produce the same complaint.