Objective: There is limited information regarding transmasculine approaches to gender-affirming voice therapy. Specifically, behavioral interventions to effectively and safely create desired vocal characteristics are lacking in the literature, creating an imbalance in therapeutic approaches for those seeking voice masculinization compared to feminization therapy.  The purpose of this study was to examine voice masculinization therapy and define therapeutic approaches, characterize acoustic outcomes over successful intervention, and describe the impact of therapy on vocal health measures in transmasculine and non-binary individuals.

Methods: An in-depth retrospective medical review of seven transmasculine/non-binary adults (aged 23-59 years) assigned-female-at-birth who completed voice masculinization therapy at the University of Cincinnati's Gender-Affirming Voice Center was completed. All participants had documented voice therapy goals, pre/post-therapy acoustic recordings, and behavioral health information relevant to vocal hygiene (e.g., smoking history, reflux diagnosis). An acoustic analysis to compare pitch and formants (F) 1 and 2 was calculated to evaluate acoustic changes related to masculinization of the voice. Assessment of vocal quality and detection of abnormal voice behaviors was completed using cepstral peak prominence (CPP) for vocal quality and formant-estimated vocal tract length (VTL) for muscle tension.

Results: This study is ongoing and will continue enrollment until January 2026. Preliminary results indicate that 7/7 participants had patient-tailored pitch, resonance, intonation, and vocal health goals. Only 1 participant had a gender-neutral pitch goal. On average, participants decreased speaking fundamental frequency in sustained /a/ by 2.74 semitones (ST), in CAPE-V sentences by 2.65 ST, and in Rainbow Passage sentences by 1.09 ST. On average, participants decreased their F1 by only 3.72 Hz and F2 by 82.17 Hz, indicating darker resonance. VTL was maintained throughout therapy, supporting the hypothesis of limited circumlaryngeal muscle tension. Further analysis will include CPP acoustics as well as paired t-test comparing pre- and post-data for acoustic measures and Cohen’s d to calculate the effect size once we have completed recruitment.

Conclusion: All established goals included a wide range of voice-related parameters to address masculinization. Acoustic parameters showed trends toward masculinization, supporting these goals as ways to facilitate closer alignment with their desired voice while maintaining vocal health.