Objective: Compare the rates of change with age in tests of hearing function that measure the peripheral and central segments of the auditory system.
Design: Cross-sectional cohort study.
Participants: Two hundred forty-one volunteer members of a dementia surveillance cohort aged 71 to 96 yrs selected by having sufficient and symmetric auditory function to perform central auditory tests.
Results: Measures of central auditory function declined with age at a faster rate than did measures of peripheral auditory function. The mean distortion product otoacoustic emission thresholds at 1, 2, and 3 kHz (Distortion Product Otoacoustic Emissions1,2,3) increased 0.34 dB/yr (95% C.I. 0.07, 0.60) or 0.45 standard deviations (S.D.)/decade, whereas the pure-tone threshold average of 1, 2, and 3 kHz (PTA1,2,3) increased by 0.5 dB/yr (95% C.I. 0.32, 0.81) or 0.59 S.D./decade. The auditory-evoked potential latencies for wave V of the Auditory Brain Stem Response, Pa of the middle latency response, and P2 of the late latency response did not vary by age. The mean Synthetic Sentence Identification test with ipsilateral competing message scores dropped 1.7 percentage points (95% C.I. -2.2, -1.2) per year or 0.78 S.D./decade, which was significantly greater than the drop with age in either the Distortion Product Otoacoustic Emissions1,2,3 or the PTA1,2,3. After adjustment for drop in hearing threshold level with age, the decline in Synthetic Sentence Identification test with ipsilateral competing message was still significant and averaged 1.1 percentage points per year (95% C.I. 1.8, -0.88).
Conclusion: Central auditory function is a prominent component of presbycusis and should be assessed routinely. Rehabilitative measures for presbycusis should take central auditory function into account.