Two reports of vibratory measurements published recently in this journal under the same title describe the vibratory cycle of the normal larynx. Part I of the study 3 presented a series of detailed measurements of the glottic wave under different conditions of normal voice production. Part II 4 demonstrated some of the unusual vibratory patterns which form the vocal response of the larynx to the demands of daily use. For these studies, a series of normal subjects were photographed with an ultra-high speed Fastax camera during controlled episodes of phonation and the films were subjected to frame by frame analysis. Selected pictures from typical scenes were enlarged for accurate measurements, and a number of new observations regarding the vibratory cycle of the normal larynx were recorded. The results were transcribed graphically in norm measures as indicated in Fig. 1. The terms Open Quotient and Speed Quotient* were employed to describe