Effects of Acoustic Speech Variation on Personality Trait Perception

Abstract

This thesis examines acoustic properties of speech which influence perceptions of personality traits, specifically charisma. The following questions are addressed: How does amplitude variation influence ratings of dominance (i), how does voice quality affect personality trait attribution (ii), and how does allophonic variation affect ratings of charisma (iii). Chapter 2 addresses question (i), finding that certain linguistic levels (increased amplitude in sentence and syllable levels) affected dominance ratings while others (increased amplitude at word level and reduction at syllable level) did not. Increased sentence amplitude increased dominance ratings while increased syllable amplitudes had inverse effects. Additionally, two types of dominance were examined (social and physical dominance) but no statistically significant differences were found between the two. Chapter 3 examines question (ii). All voice qualities investigated (modal, creaky, breathy, nasal, and smiling) were found to be statistically significant. Effect sizes for statistical significance varied for each voice quality. Creaky voice (rated the lowest/ most negative) and smiling voice (rated the highest/most positive) had the strongest effects. Chapter 4 examines question (iii). Experiment 1 (in-person) and Experiment 2 (online) examined the effects of allophonic variation, final consonant devoicing (FCD), and /t/ variation, on ratings of charisma. Experiment 1 found statistically significant rating differences for FCD. Final voiced items were rated higher compared to devoiced ones. For the /t/ variation, only speaker differences were found to be statistically significant. Experiment 2 showed no statistically significant results for FCD, whereas /t/ variation found statistical significance for [t] productions versus the glottal stop, and for flap productions versus the glottal stop. No rating differences were found between [t] and flap. Overall, this thesis demonstrates that some acoustic variations within speech affect personality trait ratings, specifically charisma, while others do not. I discuss reasons for these outcomes and their utilization in various domains, including AI.