On the Air Resistance and the Bernoulli Effect of the Human Larynx

A model of the larynx has been constructed, and measurements of air resistance for this model have been made. The dc resistance R was measured for diameter d of the glottis from 0.1 to 3.2 mm, for subglottic pressures Ps up to 64 cm water and/or volume velocities v up to 2 liters/sec. To a good approximation, the resistance was equal to the sum of a frictional term, proportional to d−3, and a turbulence term, proportional to vd−2. The frictional term dominates at small diameters and/or small volume velocities, with v proportional to Psd3 and the differential resistance Rd=R. The turbulence term dominates at large diameters and/or large volume velocities, with v proportional to Ps12d and Rd= 2R. Over the major region the pressure at the outlet of the glottis was about −12PB, where PB is the kinetic pressure in the glottis, and the pressure over the entry of the glottis was about 1.37PB. The applicability and the implications of the results to various problems of normal voice production are discussed.