It is widely recognized that objective evaluation of vocal function is necessary in treating vocal disorders . The purpose of this report is to learn the clinical significance of measurement of the vocal function during comfortable phonation to serve as a guideline in studying various laryngeal diseases . Using a phonation analyzer(PS-77), air flow rates, intensities and fundamental voice frequencies during phonation were measured simultaneously for 402 patients and used as aerodynamic

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... s. These results were then compared with the range of normal subjects. The following results were obtained .(1) Air flow rate is subject to change depending on glottis resistance and expiratory force. (2) While clinical application of this examination is useful to confirm the degree of insufficiency of the vocal closure by increased flow rate and the hypertensive mode of the vocal folds by decreased flow rate during stable phonation, values of these parameters do not enable direct diagnosis of laryngeal dysfunction. (3) These tests may aid in evaluating how to change the phonatory function after treatment.