Can you tell whether a person has COVID-19 by their cough?

Research says it’s highly unlikely you, or even a professional, can accurately identify the origin of wheezes, hems and heaves, and whether it’s the flu or just a drink that’s gone down the wrong tube.

Instead, most people believe the more nasty the hack the more dangerous the disease being shared by the unhappy carrier.

“Participants in four studies judged whether cough and sneeze sounds were produced by people infected with a communicable disease or not,” reported the authors of Sounds of Sickness, a study published by the Royal Society of Biological Sciences.

“Instead, the more disgusting they perceived a sound to be, the more likely they were to judge that it came from an infected person (regardless of whether it did). Thus, unlike research indicating perceivers can accurately diagnose infection using other sensory modalities (e.g. sight, smell), we find people over-perceive pathogen threat in subjectively disgusting sounds.”

Coughs are the most common reason for people to head to the doctor and while a lot has been learned in the last 30 years as to how to manage expectorations with different causes, but little agreement on a specific diagnostic process.

Dividing cough sounds into their different causes has been a topic for study since at least the 1980s.

Just automate it

Respiratory companies will welcome the news, which may support efforts to automate diagnosis of lung conditions.

Around 15 per cent of deaths worldwide are caused by infectious diseases, and while humans have evolved to identify infection via stimuli such as smell, sight and touch, people cannot accurately tell from sound whether a person is infectious — and therefore should keep their distance.

The outcome of four studies suggested that people may integrate sickness sound information with other sensory information, or that because coughs and sneezes are such strong physiological mechanisms the sound variation of an infectious hack is so slight only an algorithm could detect it.

The study cited research funded by ResApp (ASX:RAP), which has built technology around identifying what cough is produced by which disease, that suggests algorithms can ‘hear’ the small variations in disease from sound.

ResApp is the only ASX company attempting to build a device or system that identifies sounds. It has been approved for use with adults in Australia and Europe, but rejected by the powerful US Food and Drug Administration (FDA).

The company has been buoyed by the rise of telehealth around the world as it has pitched itself as a tool to assist doctors unable to conduct in-person physical examinations.

The standard evaluation of a cough is for a doctor to do a physical examination and look at the patient’s medical history to ferret out what might be the cause of a cough.

That might be followed by imaging of the lung, such as by a CT scan or an MRI to pin down asthma or something more serious like chronic obstructive pulmonary disease.

Companies like Cyclopharm (ASX:CYC) are operating in this field. It has developed a gas that carriers fine radioactive particles that patients breathe in before a CT scan.

Others like yet-to-be-floated 4DMedical are developing specific lung ventilation analysis software that can be used with imaging services.