Speech-in-noise processing in Autism Spectrum Disorder: electrophysiological and behavioural evidence

Li, J. (2026) Speech-in-noise processing in Autism Spectrum Disorder: electrophysiological and behavioural evidence. PhD thesis, University of Reading. doi: 10.48683/1926.00128451

Abstract/Summary

Recognising speech in the presence of competing sounds requires listeners to effectively process both acoustic and semantic information. Autistic individuals often experience greater difficulties with speech-in-noise (SiN) processing, but the underlying mechanisms remain unclear. Existing electrophysiological (EEG) research has primarily focused on auditory-level processing in autism and frequently relies on short, discrete stimuli, such as tones or single words. As a result, higher-level semantic processing and its interaction with auditory mechanisms during continuous speech remains largely unexplored. This thesis addresses these gaps through three studies combining EEG and behavioural measures to investigate SiN processing in autistic and non-autistic adults. Study 1 evaluated listeners’ use of acoustic cues (i.e., difference in speaker gender and spatial location) to attend to a speaker amid competing voices. While both groups benefited from these cues, autistic participants showed lower accuracy and smaller improvements over time. Study 2 examined the impact of background music on semantic processing using a sentence acceptability task. Autistic participants showed lower accuracy and attenuated N400 responses to semantic incongruities, reflecting difficulties with semantic integration. Unlike non-autistic participants, whose behavioural and neural responses varied with lyric intelligibility, autistic participants showed minimal variation across conditions. Study 3 explored auditory and semantic processing in the presence of intelligible or unintelligible background speech using the same task. Autistic participants showed reduced auditory encoding, as captured by EEG-derived temporal response functions, and delayed semantic processing reflected by N400 latency. While non-autistic participants adjusted their auditory and semantic processing according to the intelligibility of the background speech, autistic participants showed no such modulation. Overall, these findings offer new insight into SiN processing in autism, highlighting inefficient auditory and semantic processing, and a consistent lack of modulation in response to different noise types. This reduced flexibility in adapting to complex listening conditions indicates broader differences in processing strategies.

Item Type	Thesis (PhD)
URI	https://centaur.reading.ac.uk/id/eprint/128451
Identification Number/DOI	10.48683/1926.00128451
Divisions	Life Sciences > School of Psychology and Clinical Language Sciences
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