Objective High-Speed Videoendoscopy Measures of Vocal Fold Vibration During Semi-Occluded Vocal Tract Exercise

Much of what is known about semi-occluded vocal tract (SOVT) exercise is based on modeling and theoretical constructs. This exploratory study aimed to address the need for direct kinematic data from laryngeal imaging to investigate the impact of SOVT exercise on the vibratory characteristics of the vocal folds.

A small sample of two participants, with no history of voice disorder, underwent transnasal, flexible fiberoptic endoscopy connected to a custom-built high-speed videoendoscopy (HSV) system. Participants were asked to perform the following tasks: a sustained vowel (/i/), sustained straw phonation, another repetition of the /i/ vowel, and straw phonation into a small cup of water. Physiologic measures during the phonation tasks, derived from the HSV playback, were analyzed and compared to the SOVT tasks.

Glottal attack time trended toward longer, positive values during SOVT exercises, indicating "breathier" onsets, compared to sustained phonation preSOVT. This trend was more pronounced for straw phonation into a cup of water than for straw phonation alone. The results for glottal contact closed-quotient were more variable. Both participants had some degree of supraglottic squeezing during phonation, which was not present during SOVT production.

Although a small sample was investigated, this study reports clinically significant findings, providing some of the first insight into vocal fold vibratory physiology during SOVT production, as measured by direct laryngeal imaging. Additionally, this study offers descriptions of objective measures of manual HSV analysis to a literature base in need of validation of such measures.