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Description
Age-related cochlear synaptopathy (CS) degrades neural coding of sound, as reflected in envelope and frequency following responses (EFR/FFR). However, its perceptual consequences remain unclear. This study examined whether age-related declines in subcortical neural sound representation are reflected in deficits in perceptual discrimination of temporal and spectral features. Two groups of young (yNH; n = 20) and older normal-hearing adults (oNH; n = 20) completed three perceptual tasks in quiet and noise: (1) formant-frequency and (2) formant-bandwidth discrimination tasks, both targeting sensitivity to spectral information at low frequencies; and (3) a temporal envelope discrimination task assessing sensitivity to the shape of temporal envelopes at high frequencies. Stimuli consisted of single-formant harmonic complexes (113-Hz fundamental) and amplitude-modulated tones (4-kHz carrier, 113-Hz modulation). FFRs were recorded using dynamic versions of these stimuli, with parameters varying continuously over 1 second. The envelope component of the FFR was reduced in oNH compared to yNH, whereas the temporal fine-structure component was preserved. However, perceptual performance did not differ significantly between groups in any task, either in quiet or in noise, and did not correlate with global FFR metrics. This dissociation suggests that age-related declines in subcortical neural encoding are not directly reflected in basic perceptual discrimination. These findings are consistent with the possibility that the perceptual impact of CS is subtle or mitigated by central compensatory mechanisms. Our study provides a detailed characterization of how neural representations of dynamic sounds are reshaped with age, which is critical for refining computational models of CS.