Cross-linguistic Prosodic Analysis of Autistic and Non-autistic Child Speech in Finnish, French and Slovak

Prosodic differences in autism are well-documented, but cross-linguistic evidence remains limited. This study investigates prosody in autism across a multilingual corpus of Finnish, French, and Slovak speakers. 88 acoustic features from over 5,000 inter-pausal units were extracted, and data were reduced via Principal Component Analysis (PCA) and analyzed using Linear Mixed-Effects Models (LMMs). Cross-linguistically, autistic speakers exhibited increased general intensity variability and a clearer, less breathy voice quality (higher Harmonics-to-Noise Ratio and alpha ratio), alongside reduced temporal intensity dynamics and lower central f0. Monolingual analyses revealed language-specific nuances: Slovak results aligned with cross-linguistic f0 patterns but diverged on voice quality, while Finnish results mirrored the broader voice quality findings. These results emphasize including voice quality and intensity dynamics in the study of possible language-independent markers of autism, alongside traditional pitch measures. The findings challenge deficiency-based models, suggesting instead a complex, acoustically distinct prosodic profile across languages.