Introduction

Adduction of the larynx at the level of the vocal folds and arytenoid cartilages is a primary peripheral and mechanical control variable in phonation. Laryngeal qualities from breathy to constricted phonation are dependent on glottal adduction (e.g., Scherer, Gould, Titze, Meyers and Sataloff, 1988b). A noninvasive measure of laryngeal adduction is therefore of importance and interest for both theoretical and applied purposes.

The electroglottograph is a noninvasive instrument that provides a signal related to glottal kinematics (ref. Baken, 1987 and 1992, Colton & Conture, 1990, and Orlikoff, 1991, for a relatively thorough review of principles, history, pitfalls, and relationships to laryngeal function). Values of the electroglottograph (EGG) wave form function correspond strong ly to the amount of contact area between the two vocal folds, but not in ways completely understood or straight-forward (Childers & Krishnamurthy, 1985; Childers, Alsaka, Hicks & Moore, 1987; Anastaplo & Karnell, 1988; Scherer, Druker & Titze, 1988a; Childers, Hicks, Moore, Eskenazi & Lalwani, 1990; Titze, 1990). The shape of the EGG waveform may be related to specific configurations and motions of the vocal folds relevant to normal, abnormal, and trained voices (e.g., Fourcin, 1974; Titze, 1984, 1989; Dejonckere & Lebacq, 1985; Childers, Alsaka, Hicks & Moore, 1986; Baken, 1987; Scherer & Titze, 1987; Gerratt, Hanson & Berke, 1987; Painter, 1988; Motta, Cesari, Iengo & Motta, 1990; Brown & Scherer, 1992).

This study examines a simple measure of the waveform of the electroglottograph, called the EGGW measure, to determine its relationship to other measures of adduction, including a direct measure of the gap between the vocal processes of the arytenoid cartilages. The results will show that EGGW appears to be a significant measure of adduction, at least for the limited number of subjects and phonatory conditions reported in this study.

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