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

• Published in: Hearing research 2023-07, Vol.434, p.108771-108771, Article 108771
• Main Authors: Bologna, William J., Molis, Michelle R., Madsen, Brandon M., Billings, Curtis J.
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation - methods; Aged; Aging; Brain Stem; Envelope following response; Forward masking; Frequency following response; Glimpsing; Hearing - physiology; Humans; Interrupted speech; Noise - adverse effects; Speech; Speech Perception - physiology
• ISSN: 0378-5955; 1878-5891; 1878-5891
• DOI: 10.1016/j.heares.2023.108771

•Temporal coherence of brainstem coding of glimpses is less precise in older adults than younger adults.•Magnitude of the brainstem responses is lower in adults with poorer hearing sensitivity than those with better hearing sensitivity.•Shorter duration glimpses are coded less robustly than longer glimpses.•Glimpses are coded less robustly when interrupted by noise than by silence. Difficulty understanding speech in fluctuating backgrounds is common among older adults. Whereas younger adults are adept at interpreting speech based on brief moments when the signal-to-noise ratio is favorable, older adults use these glimpses of speech less effectively. Age-related declines in auditory brainstem function may degrade the fidelity of speech cues in fluctuating noise for older adults, such that brief glimpses of speech interrupted by noise segments 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, 210 ms) and interrupted by silence or intervening noise. Responses from adults aged 23–73 years indicated that both age and hearing sensitivity were associated with EFR temporal coherence and response magnitude. Age was better than hearing sensitivity for predicting temporal coherence, whereas hearing sensitivity was better than age for predicting response magnitude. Poorer-fidelity EFRs were observed with shorter glimpses and with the addition of intervening noise. However, losses of fidelity with glimpse duration and noise were not associated with participant age or hearing sensitivity. These results suggest that the EFR is sensitive to factors commonly associated with glimpsing but do not entirely account for age-related changes in speech recognition in fluctuating backgrounds.