Real-Time Resonance Biofeedback for Gender-Affirming Voice Training: Usability Testing of the TruVox Web-Based...

Gender-affirming voice training (GAVT) can reduce voice dysphoria for some transgender/ gender-diverse individuals, but access is often limited by factors such as high cost and a shortage of well-trained providers. Interactive software could increase the accessibility of GAVT, but existing applications are limited in functionality, particularly in the area of resonance. This paper reports the design and usability testing of a web-based software module that provides visual-acoustic biofeedback for vocal tract resonance. This preliminary study focuses on the use of the software for voice feminization.

The resonance module, part of a larger project to develop free GAVT software called TruVox, represents resonant frequencies of the vocal tract as peaks in a real-time linear predictive coding spectrum. It features built-in resonance targets for English vowel sounds, a routine for practicing resonance modification in utterances of increasing length, and video tutorials explaining how to use the website. This paper reports the results of both online and in-lab usability testing of the software. After an unstructured (online) or structured (in-person) interaction with the software, participants completed the system usability scale (SUS) and provided qualitative feedback. Participants in the in-lab study additionally completed the intrinsic motivation inventory and produced vowel targets in one-syllable words for acoustic measurement at the start and end of the session.

Participants who completed in-lab testing rated the software with an average SUS score of 75.25, indicating acceptable-to-good usability. In their qualitative feedback, users reported that the visual-acoustic biofeedback helped them understand and control their vocal resonance; they also identified a number of areas where usability could be improved. While little acoustic change was expected in light of the short duration of the session, 8/10 participants showed a trend in the expected direction for the vowel that was practiced most extensively.

The results of this usability testing suggest that our web-based biofeedback tool has the potential to enhance resonance training in the GAVT context. Future goals to improve the app include refining our automated resonance tracking algorithm for more interpretable feedback, allowing users to set individualized resonance targets based on their own voice at baseline, and adding targets for nonbinary and transmasculine users. Clinical trials to measure acoustic changes after an extended period of interaction with the software are also planned.