COVID-19 Instant Screening test, page-566

You don't need to have a cough in order to use ResappDx. A voluntary cough does the same job. The idea is to use the sounds carried by the sharply expelled air to detect alterations in the respiratory tract produced by the target condition. There was a study reported in the media – and I have to apologise that I'm at work and don't have time to look it up – showed that there were acoustically detectable changes in lung tissue in asymptomatic Covid-positive patients.