Sensitivity to interaural phase as a function of frequency: Age effects measured with behavioral and
1Department of Otolaryngology-Head & Neck Surgery, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Temporal fine-structure processing, as measured with binaural tasks, declines with increasing age in adults. The purpose of this study was to determine whether an electrophysiological test of binaural temporal processing could be used as a proxy measure for behavioral performance to reliably capture this age dependence. The behavioral measure was the upper frequency limit for differentiating in-phase from out-of-phase tones. This was assessed in both quiet and in background noise. The electrophysiological measure was the acoustic change complex elicited by epochs of interaurally out-of-phase frequency modulation carried by tones of different frequencies. Adults with normal/near-normal hearing were tested on both measures. There were 20 participants in each of the three age groups categorized as young, middle-aged, and older. The upper frequency limit measured behaviorally declined with age. It also declined in the presence of background noise, but the noise effect was equivalent across age groups. The robustness of the acoustic change complex also declined with age and as a function of the carrier frequency. However, correlations between the behavioral and electrophysiological measures were modest at best, suggesting that the electrophysiological test as implemented in this study did not provide a robust proxy for behavioral performance.
