Voice pitch and gender in autism.

Abstract

Autistic adults are often perceived as having an atypical speech. The acoustic characteristics of these impressions prove surprisingly difficult to delineate, but one feature that does robustly emerge across different studies is higher pitch (F0 values) in autistic versus neurotypical individuals. However, there is no clear explanation why autistic individuals should have higher-pitched voices. We propose that the solution lies in the gender imbalance still prevalent in autism, which entails an overrepresentation of male participants in research on speech in autism. We analyse speech samples from a gender-balanced group of 40 autistic and 40 neurotypical adults, controlling for potential stress levels through electrodermal activity recordings. We find that autistic males tend to have higher pitch than neurotypical males, but that autistic females tend to have lower pitch than neurotypical females. The interpretation we put forth for our finding - that the autistic versus neurotypical group difference in pitch goes in opposite directions between males and females - is that autistic individuals tend to be less influenced by neurotypical gender stereotypes.Lay abstractIt is has often been observed that autistic individuals have higher-pitched voices than non-autistic ones, but no clear explanation for this difference has been put forth. However, autistic males are still dramatically over-represented in published research, including the acoustic studies that report higher pitch in autistic participants. In this study, we collected speech samples from a group of autistic and neurotypical adults that, unlike in most studies, was perfectly balanced between groups and genders. In this gender-balanced sample, pitch was significantly higher in autistic versus neurotypical men, but lower in autistic versus neurotypical women. Overall, women tend to have higher-pitched voices than men, but the magnitude of this difference is culture dependent and may be significantly influenced by the internalisation of normative expectations towards one's gender. We propose that higher pitch in autistic males and lower pitch in autistic females could be due, at least in part, to a lesser integration of sociolinguistic markers of gender. Our report shows that speech atypicality should not be operationalised in terms of systematic and unidirectional deviation from the neurotypical baseline.