Perceived closeness and autistic traits modulate interpersonal vocal communication

Vocal modulation is a critical component of interpersonal communication. It not only serves as a dynamic and flexible tool for self-expression and linguistic information but also plays a key role in social behaviour. Variation in vocal modulation can be driven by individual traits of the individual interlocutors, as well as by factors relating to the dyad, such as the perceived closeness between interlocutors. Accordingly, the current study examines the role of a) individual differences in autism-related traits, and b) perceived closeness between interlocutors on vocal modulation. Since lack of appropriate vocal modulation is often associated with Autism Spectrum Disorders we also focus on autism-related individual traits. The role of these individual and dyad-level factors on vocal modulation is tested for cultural generalizability by conducting this study in three separate samples from India, Italy, and the UK. Articulatory features were extracted from recorded conversations between a total of 85 same-sex pairs of participants and correlated with their self-reported perceived closeness (CR) to the other member of the pair and with the individual Autism Spectrum Quotient (AQ). Results indicated a significant positive correlation between interpersonal closeness and articulation area in all three samples. A significant negative correlation between AQ and articulation area was observed only in the UK sample. This study thus provides novel insights into determinants of interpersonal vocal communication and a test of their cultural generalizability.