Speech‐in‐noise understanding in older age: The role of inhibitory cortical responses

Abstract

Studies of central auditory processing underlying speech‐in‐noise (SIN) recognition in aging have mainly concerned the degrading neural representation of speech sound in the auditory brainstem and cortex. Less attention has been paid to the aging‐related decline of inhibitory function, which reduces the ability to suppress distraction from irrelevant sensory input. In a response suppression paradigm, young and older adults listened to sequences of three short sounds during MEG recording. The amplitudes of the cortical P30 response and the 40‐Hz transient gamma response were compared with age, hearing loss and SIN performance. Sensory gating, indicated by the P30 amplitude ratio between the last and the first responses, was reduced in older compared to young listeners. Sensory gating was correlated with age in the older adults but not with hearing loss nor with SIN understanding. The transient gamma response expressed less response suppression. However, the gamma amplitude increased with age and SIN loss. Comparisons of linear multi‐variable modeling showed a stronger brain–behavior relationship between the gamma amplitude and SIN performance than between gamma and age or hearing loss. The findings support the hypothesis that aging‐related changes in the balance between inhibitory and excitatory neural mechanisms modify the generation of gamma oscillations, which impacts on perceptual binding and consequently on SIN understanding abilities. In conclusion, SIN recognition in older age is less affected by central auditory processing at the level of sensation, indicated by sensory gating, but is strongly affected at the level of perceptual organization, indicated by the correlation with the gamma responses.

Visual Influences on Auditory Behavioral, Neural, and Perceptual Processes: A Review

“…These results suggest a greater reliance on visual cues during speech perception, which complements the above findings that V1/V2 is employed in CI users during auditory-only listening. Reductions in auditory-evoked gamma responses as a consequence of an altered E/I ratio have also been shown in individuals with hearing loss and are correlated with reduced response suppression and impaired speech-in-noise performance compared with individuals with normal hearing (Ross et al 2020).…”

Improved Speech in Noise Perception in the Elderly After 6 Months of Musical Instruction

“…Understanding speech in noise (SIN) is a complex skill that is subject to a fairly large age-related decline (Anderson et al, 2011). This loss is not merely attributable to a degradation of structures of the auditory periphery; more and more central and cognitive domains are shown to contribute to SIN (Nahum et al, 2008;Parbery-Clark et al, 2009;Wong et al, 2009;Strait and Kraus, 2011;Moore et al, 2014;Ross et al, 2020). A fundamental mechanism for perceiving SIN involves the transformation of a complex acoustic environment into the representation of diverse auditory objects.…”

“…Beside the utilization of low-level information and bottom-up processing, effective top-down control of early auditory stages can be assumed as well, exerted via, for example, corticofugal pathways and the medial olivocochlear bundle (de Boer and Thornton, 2008;de Boer et al, 2012). Thus, stream segregation could be mediated by cognitive processes such as working memory (Parbery-Clark et al, 2009, 2011, inhibition (Ross et al, 2020), and attention (Wong et al, 2009;Strait and Kraus, 2011;Zendel et al, 2019), which seem to be conducive to SIN. In addition, it seems likely, that the implication of cognitive functions becomes particularly important with increasing age (Zendel and Alain, 2013).…”

Binaural Background Noise Enhances Neuromagnetic Responses from Auditory Cortex

“…In previous studies, both types of response showed suppression in a paired stimulus paradigm, and therefore, both have been associated with sensory gating [30][31][32]. However, P1 and gamma activity exist in parallel and show different functional dependencies with age, hearing loss, and speech-in-noise understanding [56]. Additionally, the second onset after a 15 ms gap in the stimulus did not elicit a gamma activity, which is different from the P1.…”