Making an impression: Participant-led voice synthesis reveals the acoustic signatures of trait impressions

Listeners rapidly form trait impressions from voices, inferring multiple person characteristics within milliseconds. We employed a novel method, Self-Steered Sound Synthesis (S4), to identify and compare the acoustic signatures underlying these impressions. Participants interactively used S4 to synthesise voices expressing six person characteristics - age, masculinity, health, attractiveness, dominance, and trustworthiness - by manipulating four perceptually salient acoustic dimensions: mean pitch, pitch excursion, breathiness, and formant spacing. Masculinity, older age, and dominance were conveyed by lowering mean pitch and formant spacing, consistent with projecting the impression of a large person, and by flattening the intonation. Physical health, attractiveness, and trustworthiness were conveyed by choosing less extreme and more "typical" acoustic properties. A second perceptual experiment confirmed that the synthesised voices from Experiment 1 indeed conveyed the intended person characteristics to an independent sample of listeners, and that listeners relied on similar acoustic cues for their evaluations. From a methodological perspective, we demonstrate the robustness of S4 and present convergent evidence from two drastically different approaches, thus providing a comprehensive account of impression formation that bridges voice production (or synthesis) and perception. From a theoretical perspective, our findings agree with the hypothesis that trait impressions occur within a continuous "trait space", highlighting the graded and intercorrelated nature of different person characteristics on a perceptual and conceptual level. We extend this framework by showing that not only perceptual judgements, but also the acoustic signatures of person characteristics show intercorrelations, thus integrating acoustic cues into perceptual models of voice perception.