Phonation threshold pressure in a physical model of the vocal fold mucosa.

The vocal fold mucosa, which consists of the epithelium and the superficial layer of the lamina propria, has been modeled by a fluid encapsulated in a silicone membrane. The artificial mucosa was attached to a rigid (metal) vocal fold body and introduced into an airflow channel, creating a rectangular glottis. Flow-induced oscillation of the mucosa was achieved at various subglottal pressures and glottal diameters. Phonation threshold pressure, the parameter of interest, was lowest (on the order of 0.4 kPa) for glottal diameters between 0.0 and 0.1 mm and for fluids with the lowest viscosity. There was a consistent hysteresis effect; that is, phonation threshold pressure was always lower for oscillation offset than onset.