Can ambulatory biofeedback help a transgender woman speak at a higher pitch?

Voice feminization for transgender women remains a challenge. The fundamental frequency of the voice (fo) is one of the main parameters contributing to the perception of gender. One of the aims of voice therapy is to help transgender women acquire a new vocal motor behavior to increase their fo. We hypothesized that ambulatory biofeedback could help extend the new vocal behavior to daily life.
This prospective case study assessed the impact of two weeks of ambulatory vibrotactile biofeedback (VTBF) applied to one transgender woman, following two weeks of voice therapy (three 60-minute sessions). The VTBF was activated when the participant’s voice was lower than 150 Hz for more than 500 ms and was accompanied by two 60-minute counseling sessions.
The results showed that mean fo monitored in daily activities tended to increase following the two weeks of voice therapy (Δ = 8 Hz or 1 semitone) and then increased significantly immediately after the two weeks of VTBF (Δ = 13 Hz or 1.5 semitones). The increase in mean fo from day to day and the decrease in the activation percentage from the first to the second week of VTBF (Δ = 6%) indicated a gradual integration of the motor behavior, making it possible to achieve the targeted female frequency.
The results suggest that ambulatory VTBF helped the participant to generalize the techniques acquired during the voice therapy sessions to real-life communication situations. These results are promising for therapeutic programs that integrate tools that can be used outside the clinical context.