Acoustic and perceptual evidence relevant to sexual selection in human voice dimorphism.

Male and female voices differ markedly in pitch and timbre. Previous work suggests that fundamental frequency (F0) and formant dispersion (Df) correlate with body size, but whether these associations hold within each sex and whether subtle acoustic changes affect social perception remain unclear. We integrate acoustic measurements and perceptual experiments to dissect the roles of F0 and Df in signaling height and guiding social judgments. Acoustic data from 40 males and 40 females showed that F0 exhibited a substantial sex difference but little evidence of a within-sex association with height, whereas Df showed substantial sex differences and more limited, vowel-specific within-sex height associations, with the clearest evidence observed for female /a/ Df. In the perception module, 90 raters evaluated voices manipulated by ±1 just-noticeable difference (JND) in F0 or Df. Across the four evaluator-stimulus conditions, Df produced larger estimated perceptual effects than F0 within each corresponding rating task. Together, these findings suggest that Df may retain some height-related information while contributing to social voice perception.