Voice-based Judgments of Sex, Height, Weight, Attractiveness, Health, and Psychological Traits Based on Free Speech Versus Scripted Speech

How do we perceive others based on their voices? This question has attracted research and media attention for decades, producing hundreds of studies showing that the voice is socially and biologically relevant, but these studies vary in methodology and ecological validity. Here we test whether vocalizers producing read versus free speech are judged similarly by listeners on ten biological and/or psychosocial traits. In perception experiments using speech from 208 men and women and ratings from 4,088 listeners, we show that listeners' assessments of vocalizer sex and age are highly accurate, regardless of speech type. Assessments of body size, femininity-masculinity and women's health also did not differ between free and read speech. In contrast, read speech elicited higher ratings of attractiveness, dominance and trustworthiness in both sexes and of health in males compared to free speech. Importantly, these differences were small, and we additionally show moderate to strong correlations between ratings of the same vocalizers based on their read and free speech for all ten traits, indicating that voice-based judgments are highly consistent within speakers, whether or not speech is spontaneous. Our results provide evidence that the human voice can communicate various biological and psychosocial traits via both read and free speech, with theoretical and practical implications.