because of the vibratory energy present, but it is capable of dynamic variation.

For the lowest tones, only the thyroarytenoid muscles are active, but as the pitch rises, the cricothyroids enter the action, which begins to lengthen the folds. As longitudinal tension increases, the glottis tends to develop a gap in the middle. To counteract the tendency, the lateral cricoarytenoids are brought into action, pulling forward on the muscular process of the