Glottal area and vibratory patterns studied with simultaneous stroboscopy, flow glottography, and electroglottography

The purpose of the present study was to examine the relationship between variations in glottal area and vibratory patterns during phonation studied with stroboscopy and glottographic methods. Two normal speaking male and three female subjects were examined by means of simultaneous stroboscopy, flow glottography, and electroglottography. Estimations were made of the glottal area from pressure and flow data using the formula described by van den Berg. Significant correlations were found for the male phonations between estimations and measurements of the minimum glottal area (glottal insufficiency). Estimations of the peak glottal area were also significantly correlated to measured peak glottal area for values below 25 mm2. The estimated minimum area tended to be higher, whereas the estimated peak area values were lower than the corresponding glottal area measurements. This might be explained by variations in glottal and supraglottal geometry for different modes of phonation and by sub- and supraglottal acoustic interaction. Several glottographic parameters for the male phonations were highly correlated with the measurements of glottal insufficiency and also differed significantly between normal, pressed, and breathy hypofunctional modes of phonation. The presence of a hump in the first part of the closed phase for the flow glottogram seems to indicate that a clearly visible mucosal wave is present during vocal fold vibration.