Long-Term Effects of Gender-Affirming Hormone Therapy from Adolescence to Adulthood on Voice

The primary aim of this study was to evaluate vocal outcomes in adult transgender men and transgender women who initiated gonadal hormone suppression (GHS) and gender-affirming hormone therapy (GAHT) during adolescence. The secondary aim was to explore the influence of timing and type of GHS and voice interventions on vocal parameters.

In this cross-sectional study, 88 transgender men and 23 transgender women who had received GAHT for 5-10 years were compared with 12 cisgender men and 17 cisgender women. Voice recordings of a sustained vowel, reading a phonetically balanced text, and spontaneous speech were collected using Praat software. Fundamental frequency (f_o), voice intensity, and Acoustic Voice Quality Index (AVQI) were analyzed.

Transgender men exhibited f_o values similar to cisgender men across all speech tasks. transgender women had significantly higher f_o than cisgender men but often significantly lower than cisgender women in the reading task and spontaneous speech. Transgender women had lower voice intensity than cisgender men, while similar to that of cisgender women. No significant differences were found in AVQI scores between groups, although a high proportion of participants in all groups presented very mild dysphonia. Transgender women who began GHS with GnRHa at earlier pubertal stages tended to have higher f_o than those who started later with cyproterone acetate. Phonosurgery appeared to increase f_o, while the impact of voice training was inconsistent.

Voice masculinization in transgender men who initiate GAHT during adolescence typically results in vocal characteristics comparable to those of cisgender men. In transgender women, earlier GHS may help preserve a more feminine voice, but complete alignment with cisgender women is not guaranteed (if this is the goal), especially in reading and spontaneous speech. These findings underscore the importance of early pubertal intervention and access to individualized voice care, including speech-language pathology support for trans persons.