What Contributes to Masculine Perception of Voice Among Transmasculine People on Testosterone Therapy?

Voice is a highly salient and complex signal that people use to categorize another's gender. For transmasculine individuals seeking to align their gender expression with their gender identity, vocal presentation is a major concern. Voice-gender incongruence, where one's voice does not match their gender identity, can lead to vocal strain, fatigue, emotional distress, and increased risk of suicidality. Testosterone therapy, which uses exogenous testosterone to masculinize or androgynize the voice and other secondary sexual characteristics in individuals assigned female at birth, is one method to address this issue. However, many individuals remain dissatisfied with their voice post therapy, indicating that hormonal voice modification is a complex process not fully understood. In the present study, we use unmodified voice samples from 30 transmasculine individuals undergoing testosterone therapy and utilized multivariate analysis to determine the relative and combined effects of four acoustic parameters on two measures of gender perception. The results show that transmasculine individuals' speech is perceived as equally "masculine" as that of cisgender males, with both groups being statistically categorized as male at similar rates. Although mean fundamental frequency and formant-estimated vocal tract length together account for a significant portion of the variance in gender perceptions, a substantial amount of variance in gender perception remains unexplained. Understanding the acoustic and sociolinguistic factors that contribute to masculine voice presentation can lead to more informed and individualized care for transmasculine individuals experiencing voice-gender incongruence and considering testosterone therapy. For this population, addressing voice-gender incongruence has important implications for life satisfaction, quality of life, and self-esteem.