Quantitative analysis of vocal fold vibration in vocally fatigued voice in high speed laryngoscopic images

Abstract

This study examined the vocal vibration pattern of fatigued voice by high speed laryngscopic imaging. A computer program, High Speed Video Processing (HSVP) program, was used to quantify the laryngscopic images using indices measuring glottal area, anterior-posterior length of the glottis and the width of the glottis. Twenty participants aged from 18 to 23 years (mean = 21.2 years, s.d. = 1.3 years) with normal voice were recruited to participate in a singing task. Vocal fatigue was induced through prolonged singing. High speed laryngscopic imaging was taken before and after the singing task. Images of /i/ phonation were analyzed using the HSVP program. Significant changes were found in the posterior glottal length ratio index and glottal length to width ratio index following vocal fatigue. It was hypothesized that vocal fatigue condition would lead to a compensatory hyperactive laryngeal adjustment. This lengthened the vocal folds anterio-posteriorly and made the glottis narrower. The high speed imaging technique using quantitative analysis has the potential for early identification of vocally fatigued voice.