Age-related declines in spatial hearing and temporal processing despite normal to mild hearing loss

Older adults often show deficits on suprathreshold listening tasks despite normal or near-normal hearing, suggesting contributions beyond audibility. We examined age-related performance on two sound-field spatial-hearing tasks and two headphone-based auditory-processing tasks in 48 adults aged 21-78 years with normal hearing or no more than mild loss through 4000 Hz. Spatial acuity was assessed using minimum audible angle (MAA) for 500- and 4000-Hz narrowband noise under on- and off-axis conditions at signal-to-noise ratios (SNRs) from -3 to -12 dB. Spatial speech-in-noise (SSIN), Temporal Fine Structure (TFS), and Spectro-Temporal Modulation (STM) performance were also measured. Mixed-effects models showed significant age effects on all four tasks after adjustment for pure-tone average (PTA). MAA age effects were strongest off-axis, particularly at 4000 Hz, whereas SSIN age effects increased as SNR became more adverse. TFS and STM performance also declined with age independently of PTA. When extended-high-frequency thresholds replaced PTA, age remained significant for MAA, SSIN, and TFS but not STM. Raw cross-task correlations survived false-discovery-rate correction, but none remained significant after controlling for age. Nevertheless, hierarchical regression showed that TFS and off-axis 4000-Hz MAA each explained additional variance in difficult SSIN performance beyond age and PTA, with the final model explaining 53.1% of variance. Thus, aging is associated with suprathreshold spatial and temporal-processing deficits not explained primarily by standard audiometric thresholds.