Evidence against the influence of aging on distortion-product otoacoustic emissions.

Previous research has reported reduced otoacoustic emission amplitude as a function of age. In each study, however, interpretation of findings was confounded by age-related hearing loss. The present study was designed to re-evaluate the contribution of age and peripheral hearing loss on the prevalence and amplitude of distortion-product otoacoustic emissions (DPOAEs) by controlling for degree of peripheral hearing loss. Twenty subjects were divided into four age ranges. All subjects in each group had 15 dB HL or better thresholds from 0.25 through 8 kHz and normal immittance findings. DPOAE audiograms recorded at three intensity levels and input/output functions recorded at six discrete frequencies showed no significant differences in amplitude or noise level between age groups. Findings indicate that when the degree of peripheral hearing loss is adequately controlled, there is no direct effect of advanced age on DPOAE measures. Clinical implications are discussed.