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.