ABSTRACT
OBJECTIVE: To investigate how listeners use fundamental frequency, implied vocal tract length, and source spectral tilt to infer speaker gender. METHODS: Sound files each containing the vowels /i, æ, É, u/ interspersed by brief silences were synthesized. Each of the 210 stimuli was a combination of 10 values for fundamental frequency and 7 values for implied vocal tract length (and the associated formant frequencies) ranging from male-typical to female-typical, and 3 values for source spectral tilt approximating the voice qualities of breathy, normal, and pressed. Twenty-three listeners judged each synthesized "speaker" as "female" or "male." Generalized linear mixed model analysis was used to determine the extent to which fundamental frequency, implied vocal track length, and spectral tilt influenced listener judgment. RESULTS: Increasing fundamental frequency and decreasing implied vocal tract length resulted in increased probability of female judgment. Two interactions were identified: An increase in fundamental frequency and also a decrease in source spectral tilt (more negative) resulted in a greater increase in the probability of female judgment when the vocal tract length was relatively short. CONCLUSIONS: The relationships among fundamental frequency, implied vocal tract length, source spectral tilt, and probability of female judgment changed across the range of normal values, suggesting that the relative contributions of fundamental frequency and implied vocal tract length to gender perception varied over the ranges studied. There was no threshold of fundamental frequency or implied vocal tract length that dramatically shifted the perception between male and female.
