Gender differences in vocal fold contact computed from electroglottographic signals: the influence of measurement criteria

EGGW is a phonatory parameter that can be derived from electroglottographic (EGG) signals and used to infer the relative degree of vocal fold contact. Vocal fold models predict that men will exhibit medial bulging of their vocal folds during phonation but women will not. These models lead us to expect gender differences in the magnitude of EGGW. Nevertheless, significant gender differences in EGGW for adults with normal voices have not been documented in previous studies when EGGW was computed from criterion lines placed at 25%-40% of the amplitude of the uninverted EGG wave form. We hypothesized that EGGW would better reflect gender differences in vocal fold adductory patterns if EGGW was computed from portions of the wave form that were associated with more vocal fold contact. EGGW was measured for seven men and seven women with normal voices. When EGGW was computed from segments of the wave form that were associated with relatively greater vocal fold contact (i.e., using criterion levels of > or = 55%), findings were consistent with the gender-specific adductory patterns that have been proposed from vocal fold models. Guidelines for appropriate placement of criterion lines when computing EGGW are discussed.