Analysis of longitudinal phase differences in vocal-fold vibration using synchronous high-speed videoendoscopy and electroglottography.

OBJECTIVE This investigation used synchronous high-speed videoendoscopy and electroglottography (EGG) to systematically study contact and separation behavior along the length of the vocal folds. DESIGN Repeated measures. METHODS Facilitated by EGG and digital kymograms derived at 20%, 35%, 50%, 65%, and 80% of the posteroanterior length of the vocal folds, the pattern of vocal-fold contact and separation was determined for seven female and seven male vocally healthy subjects while producing "breathy," "comfortable," and "pressed" phonations. RESULTS The female subjects consistently used an anterior-to-posterior contact pattern and posterior-to-anterior separation pattern when producing a breathy or comfortable voice, with several using a simultaneous pattern of contact and/or separation for pressed phonation. The male subjects showed more variable "zipperlike" separation patterns, but consistently used a simultaneous contact pattern for pressed voice that was also commonly used when producing comfortable phonation. CONCLUSIONS Findings indicate longitudinal phase differences in vocal-fold vibration are both common and expected in vocally healthy speakers. The implications for vocal assessment, as well as for the use and interpretation of the EGG signal, are discussed.