Age-related temporal processing deficits: The relationship between gap detection and temporal cue discrimination

Abstract

Temporal processing abilities are crucial for encoding auditory information. These abilities decline with age, particularly impacting the ability to perceive brief temporal cues. Furthermore, age-related temporal processing deficits appear to be particularly detrimental for speech processing with degraded auditory input, such as that experienced by cochlear-implant users. The goal of this study was to investigate how aging affects performance on different auditory temporal processing tasks in individuals with normal hearing presented simulated electric hearing. First, we hypothesized that reducing spectral information and increasing temporal complexity in a sound would negatively impact temporal processing, with older listeners showing greater deficits. The listeners completed a gap detection task with four stimuli varying in temporal complexity and spectral information. Gap detection thresholds were influenced by both spectral and temporal characteristics of the stimuli, as well as by the listeners’ age although no significant interaction between condition and age group were observed. Second, we hypothesized that reducing spectral information would affect listeners’ ability to discriminate between temporal speech cues, with older listeners showing more difficulty. Listeners completed a temporal cue discrimination task where they identified differences in silent interval durations using the word pair “Dish” and “Ditch” presented on a 7-step continuum, ranging from 0-60 ms of silence. Stimuli were presented in both unprocessed and vocoded conditions. Slope values of the psychometric functions for the vocoded stimuli were shallower compared to unprocessed speech, demonstrating that reduced spectral information made the task more difficult and increased reliance on temporal cues. In addition, no significant effects of age group across conditions were observed, suggesting that age did not impact performance on the temporal cue categorization task. Finally, we hypothesized that the individual variability in speech discrimination performance would correlate with gap detection thresholds. No significant correlations were found between performance on gap detection and temporal cue discrimination tasks, suggesting that these tasks may rely on different auditory, linguistic, or cognitive mechanisms. Overall, these findings highlight the importance of temporal processing for understanding speech with degraded spectral input and raise important considerations for older cochlear-implant users. Addressing temporal processing deficits through improvements in device programming may help audiologists enhance speech perception and listening experiences for individuals with cochlear implants.