Steven Bielamowicz Gerald S. Berke Jody Kreiman Bruce R. Gerratt David C. Green
UCLA Div. of Head and Neck Surgery, UCLA School of Medicine, CHS 62-132, Los Angeles, CA 90024 and VA Med. Ctr., West Los Angeles, CA 90073
Richard S. McGowan
Haskins Labs., New Haven, CT 06511
Although theoretical studies include a term for gas density in their mathematical descriptions of glottal aerodynamics, no studies have measured the effect of gas density on glottal vibration and particle velocity. This study used a constant temperature anemometer in the in vivo canine model of phonation to evaluate the effect of gas density on subglottic pressure, particle velocity, and glottal vibration by comparing phonation with air and helium. With gas flow and laryngeal nerve stimulation held constant, peak subglottic pressure was significantly greater during helium phonation (70 cm Hg) than during air phonation (62 cm Hg). In addition, peak particle velocity during helium phonation (45 m/s) was significantly greater than phonation with air (34 m/s). However, the increase in particle velocity with helium compared to air was less than predicted by the Bernoulli relationship. This loss in velocity likely represents turbulent and frictional forces at the glottal outlet.