Temporal Resolution in Regions of Normal Hearing and Speech Perception in Noise for Adults with Sloping High-Frequency Hearing Loss

In Brief Objectives: (1) To determine whether high-frequency sensorineural hearing loss (HF SNHL) is accompanied by deterioration in temporal resolution in the low-frequency region where hearing sensitivity is within normal range. (2) To evaluate whether such temporal processing deficits contribute to speech perception difficulty in noise. Design: A between-group design was employed, using subjects either with or without high-frequency hearing loss and matched by age. Temporal resolution was evaluated in amplitude modulation (AM) detection and gap detection tasks. To restrict evaluation to the low-frequency regions where the auditory sensitivity was virtually normal, low-pass noise carriers (for AM detection) and gap markers (for gap detection) were used. The impact of temporal processing deficits on speech perception was evaluated using hearing in noise tests (HINT) with varied time compression rates of the speech materials. Results: Adults with high-frequency hearing loss showed poorer performance than the age-matched normal-hearing subjects on both the AM and gap detection tasks, even though the stimuli were restricted to regions of observed normal sensitivity. With increasing time compression, listeners with HF SNHL required a larger signal to noise ratio to maintain accuracy in speech perception in adaptive HINT and exhibited a bigger decrease in score for HINTs at a fixed signal to noise ratio. Multiple regression/correlation analyses show significant correlation across the scores of AM/gap detection tasks and HINTs. Conclusions: Temporal resolution in the low-frequency region with near-normal sensitivity seems to be deteriorated in subjects with HF SNHL. They were more sensitive to increases in speech rate, suggesting that poorer temporal processing may be related to speech perception deficits in noise. Potential off-channel impact of high-frequency hearing loss of cochlear origin on the deterioration in temporal acuity was evaluated in AM- and Gap-detection tasks of low frequency region and the role of this deterioration on speech perception deficit in noise was evaluated in HINTs of varied time compression. The results are consistent with the hypothesis that the high-frequency sensorineural hearing loss deteriorates the temporal processing ability of low-frequency auditory channels. This deterioration may be related to the speech perception deficit in noisy background experienced by these subjects.