Before revision: The airborne transmission of disease-causing pathogens like the SARS-CoV-2 virus responsible for the COVID-19 pandemic is known to occur not only through violent expiratory events like coughs or sneezes , but also during activities like singing and even speech. We study, using direct numerical simulation (DNS), the transport of virus-laden aerosols generated during human speech. We show that the use of the " top-hat " formulation for steady speech flows can underestimate infection probabilities by a factor of 2-3.
After revision: The airborne transmission of disease-causing pathogens like the SARS-CoV-2 virus responsible for the COVID-19 pandemic is known to occur not only through violent expiratory events like coughs or sneezes , but also through routine activities like breathing/speaking/singing. We perform direct numerical simulations of the turbulent transport of potentially infectious aerosols in short conversations. It is shown that a two-way conversation significantly reduces the aerosol exposure compared to a relative monologue by one person and relative silence of the other. This is because the interaction of the use of the " top-hat " formulation for steady speech flows can underestimate infection probabilities by a factor of 2-3.