Fluid Dynamics of Speech: Mechanisms Underlying COVID-19 Transmission

Speech is a potent route for viral transmission in the COVID-19 pandemic. Informed mitigation strategies are difficult to develop since the relationship of speech to the exhaled flow has not been documented, nor has the aerosolization mechanism in the oral cavity been visualized. Princeton University's Howard A. Stone will document the spatio-temporal structure of the expelled air flow and detail how drops form using high-speed imaging. Specifically, phonetic characteristics of plosive sounds like "P" lead to enhanced directed transport, including jet-like flows that entrain the surrounding air. The transport features are demonstrated using order-of-magnitudes estimates, numerical simulations, and laboratory experiments. Different configurations of speakers can then be studied to understand risk of infection in casual conversations.