THE MEMBRANOUS CONTACT QUOTIENT - A NEW PHONATORY MEASURE OF GLOTTAL COMPETENCE

The membranous contact quotient (MCQ) is introduced as a measure of dy namic glottal competence. It is defined as the ratio of the membranous contact glottis (the anterior-posterior length of contact between the two membranous vocal folds) and the membranous vocal fold length. An elliptical approximation to the vocal ford contour during phonation wa s used to predict MCQ values as a function of vocal process gap (adduc tion), maximum glottal width, and membranous glottal length. MCQ is hi ghly dependent on the vocal process gap and the maximum glottal width, but not on vocal fold length, Five excised larynges were used to obta in MCQ data for a wide range of vocal process gaps and maximum glottal widths. Predicted and measured MCQ values had a correlation of 0.93, with an average absolute difference of 9.6% (SD = 10.5%), The model is better at higher values of MCQ. The theory for MCQ is also expressed as a function of vocal process gap and subglottal pressure to suggest production control potential. The MCQ measure is obtainable with the u se of stroboscopy and appears to be a potentially useful clinical meas ure.