Effects of age on brainstem coding of speech glimpses in interrupted noise

Abstract

Difficulty understanding speech in fluctuating backgrounds is common among older adults. Previous research suggests that this age-related decline may be due to increased susceptibility to forward masking and difficulty incorporating short “glimpses” of speech into a coherent auditory object. These findings may be linked via a common brainstem mechanism, such that brief glimpses of speech surrounded by noise are not faithfully represented in the neural code that reaches the cortex. This hypothesis was tested using electrophysiological recordings of the envelope following response (EFR) elicited by glimpses of speech-like stimuli varying in duration (42, 70, and 210 ms) and separated by silence or intervening noise. Responses from adults aged 23–73 years indicated that older adults produced weaker neural responses than younger adults. Across all ages, declines in EFR strength were noted with shorter glimpses of speech and with the addition of intervening noise. However, the extent of these declines was not associated with participant age. These results suggest that the EFR is sensitive to factors commonly associated with glimpsing but may not entirely reflect age-related changes that affect speech recognition in fluctuating backgrounds. [Work supported by NIH TL1TR002371, R01DC015240, R01DC012313, and VA-RR&D 5I01RX002139.]