Correlation between glottal area and photoglottographic signal in normal subjects

Photoglottography (PGG) is an established technique for depicting the vibratory patterns of the vocal folds. The present study investigates the correlation between the glottal area and the corresponding PGG signal. Six normal (five male, one female) subjects who did not use their voices professionally were investigated during constantly sustained phonation at spontaneous pitches. Laryngostroboscopy was performed in combination with PGG. The simultaneously recorded laryngostroboscopic images and PGG signals were directly digitized and stored on a computer. The correlation between the glottal area and the corresponding PGG amplitudes across each vibratory cycle of the vocal folds was calculated and they were found to be highly and positively correlated (r = 0.973, p < 0.001). The PGG signal reflects changes in the glottal area during the vibration cycle of the vocal folds. The proposed simultaneous laryngostroboscopic and PGG technique has proved to be useful for facilitating the interpretation of changes in glottal area.