Neural Timing Is Linked to Speech Perception in Noise

Abstract

Understanding speech in background noise is challenging for every listener, including those with normal peripheral hearing. This difficulty is attributable in part to the disruptive effects of noise on neural synchrony, resulting in degraded representation of speech at cortical and subcortical levels as reflected by electrophysiological responses. These problems are especially pronounced in clinical populations such as children with learning impairments. Given the established effects of noise on evoked responses, we hypothesized that listening-in-noise problems are associated with degraded processing of timing information at the brainstem level. Participants (66 children; ages, 8 -14 years; 22 females) were divided into groups based on their performance on clinical measures of speech-in-noise (SIN) perception and reading. We compared brainstem responses to speech syllables between top and bottom SIN and reading groups in the presence and absence of competing multitalker babble. In the quiet condition, neural response timing was equivalent between groups. In noise, however, the bottom groups exhibited greater neural delays relative to the top groups. Group-specific timing delays occurred exclusively in response to the noise-vulnerable formant transition, not to the more perceptually robust, steady-state portion of the stimulus. These results demonstrate that neural timing is disrupted by background noise and that greater disruptions are associated with the inability to perceive speech in challenging listening conditions.

Older Adults Benefit from Music Training Early in Life: Biological Evidence for Long-Term Training-Driven Plasticity

“…This could account for the selective relationship between extent of past music training and response timing to the CV transition in speech but not the steady-state vowel. By priming the auditory system to encode sound according to informational saliency and acoustic complexity (Strait et al, 2009;Kraus and Chandrasekaran, 2010), increased neural resources could be devoted to the most relevant acoustic features of auditory scenes. In fact, this may account for the inconsistency in group effects for neural timing in response to speech presented in quiet versus speech presented in noise: whereas the group effect in noise was driven by the Moderate group having faster timing than the Little and None groups, in quiet this was driven by poorer timing in the Little group.…”

“…1). This subcortical electrophysiologic response is a variant of the auditory brainstem response that is elicited in response to complex sounds instead of simple clicks or tones and is generated by synchronous firing of midbrain nuclei, predominantly inferior colliculus (IC; for review, see Chandrasekaran and Kraus, 2010 This individual only reported that training stopped at a "very young" age.…”

“…Over the past several years, evidence has emerged to suggest that musicians have nervous systems distinct from nonmusicians, potentially due to training-related plasticity (Moreno et al, 2009;Kraus and Chandrasekaran, 2010;Bidelman et al, 2011;Herholz and Zatorre, 2012). One of the most provocative findings in this literature is that lifelong music training may offset age-related declines in cognitive and neural functions (Hanna-Pladdy and MacKay, 2011;Parbery-Clark et al, 2012a;Zendel and Alain, 2012;Alain et al, 2013).…”

“…Even older adults with preserved peripheral function face a loss of central auditory function (Pichora-Fuller et al, 2007;Anderson et al, 2012;Ruggles et al, 2012). These age-driven deficits compound with declines in neocortical function that affect sensory and cognitive circuits (Gazzaley et al, 2005;Recanzone et al, 2011).…”

“…In speech, age-related deficits affect the neural encoding of fast-changing sounds, such as consonant-vowel (CV) transitions (Anderson et al, 2012). CV transitions pose perceptual challenges across the lifespan due to fast-changing spectrotemporal content and relatively low amplitudes (compared to vowels; Tallal, 1980).…”