An analysis of the mechanics of phonation

The mechanical work done by the chest in phonation has been measured together with the sound intensity level. The regulation of the sound intensity is done by regulating the intrapulmonary pressure. This is achieved at high intensity levels through the activity of the respiratory muscles that, together with the elastic recoil of the chest, sustain the work of phonation. At sound intensities below a critical level an additional mechanism for changing the intensity is given by a fine regulation of the opening of the glottis, thus allowing more air to escape without contributing to sound production. The contribution of the respiratory muscles, of the chest elasticity, and of the opening of the glottis to phonation at different intensity levels depend on the degree of inflation of the chest. The efficiency of phonation, as of sound production in mechanical models, seems to increase with increasing intensity and pitch.voice production; work done by chest during phonation; mechanical models of glottis generator; subglottic pressure as a function of sound level; air flow through glottis during phonation; efficiency changes of sound production; variation of sound intensity by regulating opening of glottis; variations of the area of glottis depending on extent of elastic recoil of chestSubmitted on February 10, 1964