Voice deepening under testosterone treatment in female-to-male gender dysphoric individuals

Female-to-male gender dysphoric individuals rarely access medical services for voice problems arising out of hormonal treatment leading to "voice reassignment". The aim of this study was a close monitoring of voice deepening in the first year following the commencement of testosterone treatment. Voice recordings from nine female-to-male (FTM) were analyzed with Praat software and values for speaking fundamental frequency (SFF) were calculated. Audio recordings were made prior to and within the first year (mean 55.2 weeks) of testosterone treatment at a mean of 35.4 different time points. The values for speaking fundamental frequency were compared with values taken from 21 biological men with healthy voices. The 10th to 90th percentile range of FTM overlapped with those of biological men after about 36 weeks. The mean SFF change was a decrease of 8.78 seminotes at week 52 and at this point in time no significant difference between SSF in FTM and biological men was found. Testosterone treatment led to significant voice deepening within the first year with the degree of change decreasing over time. Mean SFF change in the first year was almost a sixth and thus less than one octave but nonetheless reached an SFF comparable with biological men.