Age-dependent changes in temporal-fine-structure processing in the absence of peripheral hearing loss.

PURPOSE

In this study, the author sought to investigate if and when the ability to process temporal-fine-structure (TFS) cues deteriorates with age in adults with audiometrically normal hearing sensitivity.

METHOD

Using a cross-sectional design, the author assessed TFS sensitivity in 102 normal-hearing adults sampled from across the entire range of adulthood (ages 18-90 years), using 2 psychophysical tests for the assessment of within- and across-ear TFS processing.

RESULTS

Both types of TFS sensitivity (monaural and binaural) declined gradually starting in young adulthood, with the earliest significant deficit already apparent in early midlife (i.e., between ages 40 and 49 years). TFS sensitivity was not correlated with absolute sensitivity at the test frequency.

CONCLUSIONS

Some suprathreshold auditory processing abilities decline throughout adulthood, even when an individual's peripheral hearing is clinically normal. These deficits are not captured by a conventional, audiometric hearing assessment but may contribute to the increasing difficulties with age to identify speech in noisy environments. From a methodological point of view, the existence of such age effects warrants the use of age-matched participant groups when comparing normal and impaired peripheral hearing.