Short-Term Acoustic Effects of Speech Therapy in Transgender Women: A Randomized Controlled Trial

This study measured and compared the acoustic short-term effects of pitch elevation training (PET) and articulation-resonance training (ART) and the combination of both programs, in transgender women.

A randomized controlled study with cross-over design was used. Thirty transgender women were included and received 14 weeks of speech training. All participants started with 4 weeks of sham training; after which they were randomly assigned to one of two groups: One group continued with PET (5 weeks), followed by ART (5 weeks); the second group received both trainings in opposite order. Participants were recorded 4 times, in between the training blocks: pre, post 1 (after sham), post 2 (after training 1), and post 3 (after training 2). Speech samples included a sustained vowel, continuous speech during reading, and spontaneous speech and were analyzed using Praat software. Fundamental frequency (f _o), intensity, voice range profile, vowel formant frequencies (F _1-2-3-4-5 of /a/-/i/-/u/), formant contrasts, vowel space, and vocal quality (Acoustic Voice Quality Index) were determined.

Fundamental frequencies increased after both the PET and ART program, with a higher increase after PET. The combination of both interventions showed a mean increase of the f _o of 49 Hz during a sustained vowel, 49 Hz during reading, and 29 Hz during spontaneous speech. However, the lower limit (percentile 5) of the f _o during spontaneous speech did not change. Higher values were detected for F _1-2 of /a/, F ₃ of /u/, and vowel space after PET and ART separately. F _1-2-3 of /a/, F _1-3-4 of /u/, vowel space, and formant contrasts increased after the combination of PET and ART; hence, the combination induced more increases in formant frequencies. Intensity and voice quality measurements did not change. No order effect was detected; that is, starting with PET or ART did not change the outcome.