Simultaneous videofluorographic and dual-channel electroglottographic registration of the vertical laryngeal position in various phonatory tasks

Simultaneous tracking of the vertical laryngeal position in various phonatory tasks was performed for 2 subjects (one male, one female) using dual-channel electroglottography (EGG) and videofluorography (videofluoroscopy). The tasks included phonation on a:] with voluntary repeated (1) heightening and (2) lowering of the laryngeal position; alternation between a:] and phonation on (3) b], (4) m], and (5) the voiced bilabial fricative beta:]; and (6) production of the corner vowels a, i, u]. EGG and videofluorography agreed about the direction of changes in the vertical laryngeal position in most cases. Most disagreements were found in the amount of changes. Reasons for the discrepancies, including, for example, changes in the resting position of the larynx and anteroposterior movements of the cartilages, are discussed. It can be concluded that dual-channel EGG is a valuable clinical and pedagogical tool for the analysis of the vertical displacement of larynx in well-specified phonatory tasks. The method should act most reliably on separately phonated vowels. Its applicability for studying laryngeal biomechanics more wholistically, however, is limited.