Analysis of human glottal velocity using hot-wire anemometry and high-speed imaging.

Objectives: The aim of this study was to analyze glottal velocity and glottal opening and closure. For this purpose, we developed a miniature, flexible, hot-wire probe that can make truly instantaneous measurements of the human larynx in vivo. Methods: A miniature hot-wire tip was inserted into a flexible transnasal endoscope. Fiberscopic examination was performed transnasally so that we could observe glottal vibration using high-speed imaging. The tip of the hot-wire probe was placed just above the glottis. The position of the probe was carefully monitored and checked with another flexible endoscope. Results: Changes in velocity were recorded periodically. The velocity was higher in close proximity to the vocal folds. High-speed motion pictures were taken at a rate of 2,000 frames per second with an auxiliary light source. Conclusions: Quantitative analysis of glottal velocity is required to improve our understanding of the relationship between laryngeal physiology and acoustics in humans. To solve the problem of synchronization inaccuracy, glottal velocity was captured instantaneously in the high-speed imaging system's processor memory.