Research shows you can't tell if a person is sick by the sound of their cough

A small team of researchers at the University of Michigan has found that it is not possible to correctly identify illness in a person simply by listening to them cough. In their paper published in the journal Proceedings of the Royal Society B, the group describes an experiment they conducted with volunteers who listened to people cough, and what they learned from it.

Prior research has shown that people have an ability to recognize certain illnesses in other people. A runny nose, red eyes and clear fatigue are usually signs of the common cold, for example. And fever, sweating and clear fatigue are likely signs of the flu. Being able to recognize such symptoms helps people avoid others who are sick, thus avoiding becoming sick themselves. But what about coughing?

Anecdotal evidence suggests that people have a tendency to judge the degree of illness in other people who cough. A loud, long, wet, congestion-expelling cough is more likely to be perceived as a sign of an illness, for example, than a simple quick "clean" cough. Thus, upon hearing another person cough, others are likely to make judgments about how sick they think that person is based on nothing more than the sounds they make.

But such judgements appear to be misguided. In this new effort, the researchers tested volunteers to see if they could actually tell the difference between people coughing due to a throat tickle versus those who actually had an illness. During a pandemic, with an illness that is often first noted by a cough, it might prove useful if people could tell if coughing was due to COVID-19.

The work involved collecting multiple samples of people coughing on YouTube videos. They then played the clips individually to 200 volunteers. After each clip was played, each volunteer was asked whether the cough was a symptom of a true ailment, or just a ticklish throat. The researchers found that the volunteers were right in their diagnosis roughly half the time—no better than chance. They conclude that people need to be more careful about judging others in such a way, because they are just as likely to be wrong as right.