Pressure Distributions in Glottal Geometries With Multichannel Airflows

Abstract

Computer simulation of self-sustained oscillation of the vocal folds has been successful with application of simple Bernoulli-like driving pressures. As voice simulation is now applied to asymmetric vibration with complex mode structures that yield partial vocal fold contact, the driving pressures need refinement. Two independent approaches were used to obtain pressure distributions. The first was a high-fidelity immersed-boundary method computation and the second was a series of pressure tap measurements on scaled-up physical models. Glottal geometries were based on normal surface modes of vibration. Samples are chosen from a large inventory of measured and calculated profiles. Pressure distributions show the complexity that can exist in the driving forces on vocal fold surfaces. Qualitative similarity between computation and measurement was established for a variety of contact patterns, showing diverse pressure gradients in multiple directions. Simplified Bernoulli approaches to glottal pressure distributions are defensible when a single flow channel is preserved in vocal fold oscillation. However, when there are contact islands that produce confluence or difluence of multiple airflow channels, the pressure gradients vary profoundly. Small quantitative differences were observed between measurement and calculation, primarily due to spatial sampling.