声門上・下圧波形よりみたElectro Glottogramの解析-声の強さによる変化-

Abstract

The electroglottogram (EGG) has been used to obtain details of vocal fold vibration. Applications of the EGG, however, are limited in use for voice disorders since characteristics of EGG waveforms associated with vocal fold vibrations are still poorly understood. We analysed the EGG waveform characteristics to compare them with simultaneous measurements of supra and subglottic pressure in the normal male subject sustaining the vowel /a/ at constant pitch with different intensity levels. The results are : The periodicities of the consequent frequency are completely coincident among the EGG wave, supra and subglottic pressure waveforms at different intensity levels. With regard to the amplitude variations of the EGG waveform in the vocal cycle, the increasing amplitude corresponded with a rapid increase of subglottic pressure and a decrease of supraglottic pressure which is indicative of the closing phase of the vocal folds. The gradual fall of amplitude associated with the parting of the vocal folds corresponded with an increase of supraglottic pressure from negative values and maintenance of negative subglottic pressure. The negative flatter portion of EGG wave corresponding to the opened phase exhibited higher positive supra glottal pressure and lower pressure of the subglottic even at different sound pressure levels. When increasing the intensity during constant pitch phonation, the values of the contact quotient and contact speed index decreased, and the contact closing slope became steeper.These findings reveal the tendency of increasing vocal tension following louder vocalization. Simultaneous measurement of EGG waveforms, and supraglottic and subglottic pressures might provide useful and detailed information for understanding EGG waveforms, laryngeal dysfunction and/or research for voice disorders.