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

Purpose: Voice feminization for transgender women remains a challenge. The fundamental frequency of the voice (f_o) 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 f_o. We hypothesized that ambulatory biofeedback could help extend the new vocal behavior to daily life.Materials and methods: 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.Results: The results showed that mean f_o 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 f_o 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.Conclusions: 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. Design: Prospective case study.