Pitch and amplitude perturbation analysis using electroglottography during sustained phonation

Abstract

Elcetroglottography (EGG), an electrical impedance technique for the direct examination of vocal-fold closure, does not interfere with phonation and is noninvasive. In order to evaluate the regularity of vocal-fold vibration in normal subjects and patients with various laryngeal disorders, pitch and amplitude perturbation of EGG waves during sustained phonation were measured through a laboratory computer. These data were compared to the degree of hoarseness evaluated perceptually and by sound spectrographic analysis. Subjects produced /a/ in natural speaking voice. EGG signals were recorded by means of a Fourcin laryngograph. Fifth consecutive cycles of EGG waves during steady phonation were used for analysis. Three experts in voice pathology rated the degree of hoarseness of each voice sample. The results showed close relation between perturbation analysis of EGG waves and degree of hoarseness evaluated perceptually and by sound spectrographic analysis. There was some overlap between normal and pathological groups. It was found that amplitude perturbation was a more sensitive measure of the irregularity of vocal-fold vibration than pitch perturbation. Usefulness and limitation of this method are discussed. [Work partly supported by NIH Grant NS-13870.]