Effects of laryngeal manipulations on voice gender perception

This study aims to identify laryngeal manipulations that would allow a male to approximate a female-sounding voice, and that can be targeted in voice feminization surgery or therapy. Synthetic voices were generated using a three-dimensional vocal fold model with parametric variations in vocal fold geometry, stiffness, adduction, and subglottal pressure. The vocal tract was kept constant in order to focus on the contribution of laryngeal manipulations. Listening subjects were asked to judge if a voice sounded male or female, or if they were unsure. Results showed the expected large effect of the fundamental frequency (F0) and a moderate effect of spectral shape on gender perception. A mismatch between F0 and spectral shape cues (e.g., low F0 paired with high H1-H2) contributed to ambiguity in gender perception, particularly for voices with F0 in the intermediate range between those of typical adult males and females. Physiologically, the results showed that a female-sounding voice can be produced by decreasing vocal fold thickness and increasing vocal fold transverse stiffness in the coronal plane, changes in which modified both F0 and spectral shape. In contrast, laryngeal manipulations with limited impact on F0 or spectral shape were shown to be less effective in modifying gender perception.