Resynthesis of Transmasculine Voices to Assess Gender Perception as a Function of Testosterone Therapy

Purpose: The goal of this study was to use speech resynthesis to investigate the effects of changes to individual acoustic features on speech-based gender perception of transmasculine voice samples following the onset of hormone replacement therapy (HRT) with exogenous testosterone. We hypothesized that mean fundamental frequency (f[subscript 0]) would have the largest effect on gender perception of any single acoustic feature. Method: Mean f[subscript 0], f[subscript 0] contour, and formant frequencies were calculated for three pairs of transmasculine speech samples before and after HRT onset. Sixteen speech samples with unique combinations of these acoustic features from each pair of speech samples were resynthesized. Twenty young adult listeners evaluated each synthesized speech sample for gender perception and synthetic quality. Two analyses of variance were used to investigate the effects of acoustic features on gender perception and synthetic quality. Results: Of the three acoustic features, mean f[subscript 0] was the only single feature that had a statistically significant effect on gender perception. Differences between the speech samples before and after HRT onset that were not captured by changes in f[subscript 0] and formant frequencies also had a statistically significant effect on gender perception. Conclusion: In these transmasculine voice samples, mean f[subscript 0] was the most important acoustic feature for voice masculinization as a result of HRT; future investigations in a larger number of transmasculine speakers and on the effects of behavioral therapy-based changes in concert with HRT is warranted.