Early- and Late-Stage Auditory Processing of Speech Versus Non-Speech Sounds in Children With Autism Spectrum Disorder: An ERP and Oscillatory Activity Study

Abstract

Individuals with autism spectrum disorder (ASD) often exhibit greater sensitivity to non-speech sounds, reduced sensitivity to speech, and increased variability in cortical activity during auditory speech processing. We assessed differences in cortical responses and variability in early and later processing stages of auditory speech versus non-speech sounds in typically developing (TD) children and children with ASD. Twenty-eight 4- to 9-year-old children (14 ASDs) listened to speech and non-speech sounds during an electroencephalography session. We measured peak amplitudes for early (P2) and later (P3a) stages of auditory processing and inter-trial theta phase coherence as a marker of cortical variability. TD children were more sensitive to speech sounds during early and later processing stages than ASD children, reflected in larger P2 and P3a amplitudes. Individually, twice as many TD children showed reliable differentiation between speech and non-speech sounds compared to children with ASD. Children with ASD showed greater intra-individual variability in theta responses to speech sounds during early and later processing stages. Children with ASD show atypical auditory processing of fundamental speech sounds, perhaps due to reduced and more variable cortical activation. These atypicalities in the consistency of cortical responses to fundamental speech features may impact the development of cortical networks and have downstream effects on more complex forms of language processing.