Towards a cumulative science of vocal markers of autism: a cross-linguistic meta-analysis-based investigation of acoustic markers in American and Danish autistic children

Abstract Acoustic atypicalities in speech production are widely documented in Autism Spectrum Disorder (ASD) and argued to be both a potential factor in atypical social development and potential markers of clinical features. A recent meta-analysis highlighted shortcomings in the field, in particular small sample sizes and study heterogeneity (Fusaroli, Lambrechts, Bang, Bowler, & Gaigg, 2017). We showcase a cumulative yet self-correcting approach to prosody in ASD to overcome these issues. We analyze a cross-linguistic corpus of multiple speech productions in 77 autistic children and adolescents and 72 TD ones (>1000 recordings in Danish and US English). We replicate findings of a minimal cross-linguistically reliable distinctive acoustic profile for ASD (higher pitch and longer pauses) with moderate effect sizes. We identified novel general reliable differences between the two groups for normalized amplitude quotient, maxima dispersion quotient and creakiness. However, all these relations are small, and there is likely no one general extensive acoustic profile characterizing all autistic individuals. We identified reliable and consistent relations of acoustic features with individual differences (age, gender), and clinical feature: speech rate and ADOS sub-scores (Communication, Social, Stereotyped). Besides cumulatively building our understanding of acoustic atypicalities in ASD, the study concretely shows how to use systematic reviews and meta-analyses to guide follow-up studies, both in their design and their statistical inferences. We indicate future directions: larger and more diverse cross-linguistic datasets, use of previous findings as statistical priors, understanding of covariance between acoustic measures, reliance on machine learning procedures, and open science. Lay Summary Individuals with Autism Spectrum Disorder (ASD) are reported to speak in distinctive ways. Distinctive vocal production can affect social interactions and social development and could represent a noninvasive way to support the assessment of ASD. We systematically check whether acoustic atypicalities found in previous articles can be found in a novel and larger cross-linguistic dataset. Besides a minimal acoustic profile of ASD: higher pitch, longer pauses, increased hoarseness and creakiness, we observe large individual and linguistic variations.