Vocal fundamental and formant frequencies affect perceptions of speaker cooperativeness

In recent years, the perception of social traits in faces and voices has received much attention. Facial and vocal masculinity are linked to perceptions of trustworthiness; however, while feminine faces are generally considered to be trustworthy, vocal trustworthiness is associated with masculinized vocal features. Vocal traits such as pitch and formants have previously been associated with perceived social traits such as trustworthiness and dominance, but the link between these measurements and perceptions of cooperativeness have yet to be examined. In Experiment 1, cooperativeness ratings of male and female voices were examined against four vocal measurements: fundamental frequency (F₀), pitch variation (F₀?SD), formant dispersion (D_f), and formant position (P_f). Feminine pitch traits (F₀ and F₀?SD) and masculine formant traits (D_f and P_f) were associated with higher cooperativeness ratings. In Experiment 2, manipulated voices with feminized F₀ were found to be more cooperative than voices with masculinized F₀^, among both male and female speakers, confirming our results from Experiment 1. Feminine pitch qualities may indicate an individual who is friendly and non-threatening, while masculine formant qualities may reflect an individual that is socially dominant or prestigious, and the perception of these associated traits may influence the perceived cooperativeness of the speakers.