Tracking Voice Changes During Testosterone Hormone Replacement Therapy

Abstract

This thesis aims to describe the acoustic speech changes occurring during the first year of testosterone hormone replacement therapy (T). Using data extracted from sixty YouTube videos posted by transmasculine people documenting voice changes, this study employed a novel recruitment strategy to supplement the concern of low participant numbers in the existing literature. Measures included mean fundamental frequency (MF0) and formant frequencies, used to estimate changes in vocal tract length (VTL). Results: The MF0 of the transmasculine group reduced by 44%, from an average of 217.47 to 122.81 Hz, in one year. Their resulting MF0 fell within a standard deviation of the mean MF0 of cisgender men. Their VTL increased from an average of 14.14 to 14.90 cm, falling within two standard deviations of the mean of the cisgender men. This study, containing the largest subject pool to date, adds to the literature on voice changes during T by using publicly available recordings and including estimates of changes to vocal tract length.