Is age-related hearing loss predominantly metabolic?

Studies in animals have shown that age-related hearing loss is predominantly metabolic in origin. In humans, direct access to the cochlea is not usually possible and so non-invasive methods of assessing cochlear mechanical function are required. This study used a non-invasive assay of cochlear mechanical function, otoacoustic emissions, to examine a metabolic versus hair-cell-loss origin for age-related hearing loss. Three subject groups were examined: adult females with clinically normal hearing, adult females with age-related hearing loss, and adult males with noise-induced hearing loss. Contrasting otoacoustic emission input-output functions were obtained for the three groups, suggesting a causal relationship between age-related hearing loss and strial dysfunction.