Phonological Characteristics Shared By Questioner And Responder: A Comparison Between Individuals With And Without Autism Spectrum Disorder

How typically developed (TD) persons modulate their speech rhythm while talking to individuals with autism spectrum disorder (ASD) remains unclear. We aimed to elucidate the characteristics of phonological hierarchy in the verbal communication between ASD individuals and TD persons. TD and ASD respondents were asked by a TD questioner to share their recent experiences on 12 topics. We included 87 samples of ASD-directed speech (from TD questioner to ASD respondent), 72 of TD-directed speech (from TD questioner to TD respondent), 74 of ASD speech (from ASD respondent to TD questioner), and 55 of TD speech (from TD respondent to TD questioner). We analysed the amplitude modulation structures of speech waveforms using probabilistic amplitude demodulation based on Bayesian inference and found similarities between ASD speech and ASD-directed speech and between TD speech and TD-directed speech. Prosody and the interactions between prosodic, syllabic, and phonetic rhythms were significantly weaker in ASD-directed and ASD speech than those in TD-directed and TD speech, respectively. ASD speech showed weaker dynamic processing from higher to lower phonological bands (e.g. from prosody to syllable) than TD speech. The results indicate that TD individuals may spontaneously adapt their phonological characteristics to those of ASD speech.