The purpose of this study was to ascertain the role of chance, or consistency, in determining the rate and extent of the vibrato. Five most promising voice students of the University School of Music were secured for the study. Each was asked to sing two renditions of The Last Rose of Summer the second rendition following the first within an interval of five minutes. Recording of data in permanent form was secured by means of the strobophotographic camera, which simultaneously records duration and pitch changes, or variations of tones, in the form of a graph, with duration forming the abscissae and pitch the ordinate
