An experimental study of pulsatile flow in canine larynges

Pulsatile flow in an excised canine larynx was investigated with simultaneous recordings of air velocity, subglottal pressure, volume pow rate, and the signal from an electro-glottograph (EGG)for various conditions of phonation. Canine larynges were mounted on a pseudotrachea and sustained oscillations were established and maintained with sutures attached to cartilages to mimic the function of laryngeal muscles. The pitch and amplitude of the oscillations were controlled by varying the airflow, and by adjusting glottal adduction and vocal-fold elongation. Measurements with hot-wire probes suggest that subglottal inlet flow to the larynx is pulsatile but mostly laminar, while the exiting jet is non-uniform and turbulent. In the typical ranges of flow rate, subglottal pressure, and oscillation frequencies, the Reynolds number based on the mean glottal velocity and glottal hydraulic diameter varied between 1600 to 7000, the Strouhal number based on the same parameters varied between 0.002 and 0.032, and the Womersley number ranged from 2.6 to 15.9. These results help define the conditions required for computational models of laryngeal flow.