Correlating Speech and Voice Features of Transgender Women with Ratings of Femininity and Gender

Purpose: This study investigated which acoustic features of the voices of transgender (trans) women correlate with self- and listener ratings of voice femininity and with listener perceptions of gender. Differences between trans- and cisgender (cis) voices on these acoustic variables were also explored. Methods: Speech samples were collected from 12 trans women and 10 cis control subjects. The acoustic variables of speaking fundamental frequency (SFF), SFF variation, intensity, vowel formants, and correlates of breathiness were collected for each speaker. Speakers completed a self-evaluation of voice femininity on a five-point scale drawn from the Transsexual Voice Questionnaire for Male-to-Female Transsexuals. Excerpts of these speech samples were presented to blind listeners, who also evaluated the femininity of each voice and classified each speaker within a binary gender system. Correlations between the acoustic variables and self- and listener ratings of voice femininity and listener perceptions of gender were measured using Spearman’s rank-order coefficient. Results: Moderate-to-strong correlations were found between ratings of voice femininity and mean and maximum SFF, SFF variation, and mean intensity. These same four acoustic variables were moderately correlated with listener perceptions of gender. There were no consistent or significant correlations between voice femininity ratings or gender perceptions and minimum SFF, vowel formants, and breathiness measures. The analysis of differences between trans and cis speakers was limited by sample size. Results suggest SFF, SFF variation, and intensity—or pitch, intonation, and loudness—are appropriate targets for evidence-based voice training of trans women