Videokymography: a New High-Speed Method for the Examinationof Vocal-Fold Vibrations
J. G. Švec; F. Šram; H. K. Schutte *
Centrum péče o nemocné s poruchami hlasu, řeči a vadami sluchu, Medical Healthcom, spol. s r. o., Praha, ředitel doc. MUDr. F. Šram, CSc. Groningen Voice Research Lab
; Department of Biomedical Engineering
; University of Groningen, Nizozemsko, vedoucí prof. dr. H. K. Schutte
Otorinolaryng. a Foniat. /Prague/, , 1999, No. 3, pp. 155-162.
Videokymography is a new optical high-speed method for investigation of vibrationswhich was developed especially for examination of vocal-fold vibrations. Videokymography is basedon a modified CCD video camera, which is able to work in two different modes: standard an highspeed. In the standard mode the camera works as a normal commercial video camera providing 25images (50 interlaced fields) per second. In the high-speed mode the camera delivers images froma single selected line with frequency of almost 8000 line images/s. The successive line images are putbelow each other, creating a new videokymographic image monitoring vibration of the selected partof the vocal folds in time. A foot switch makes it possible to change instantaneously between thestandard and high-speed modes. Ordinary videolaryngoscopic equipment with a powerful endosco-pic continuous-light source is used for the videokymographic examination of the vocal folds. Boththe standard as well as high-speed images can be recorded by means of a normal video recorder,which makes the technique cost-friendly.The method is able to objectively evaluate important parameters of the vocal-fold vibration, suchas the open, opening, closing and closed phases of the vibratory cycle, propagation of mucosal waves,left-right differences in phase or amplitude, etc. Videokymography provides more detailed informa-tion on voice disorders and considerably enriches laryngostroboscopy. There is no problem forvideokymography to evaluate hoarse or unstable voices in which laryngostroboscopy fails. Also, themethod is able to reveal structural irregularities on the medial surface of the vocal fold (e.g., sulcusglottidis) which can easily be overlooked in laryngostroboscopy. It is demonstrated how combina-tion of a few laryngostroboscopic and videokymographic images can shortly and efficiently summa-rize important anatomical, physiological/pathological and vibrational properties of the laryngealtissues in various patients.
videokymography, high-speed imaging, vocal folds, vocal-fold vibration, laryngo-scopy, laryngostroboscopy.
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