Spread of COVID-19 doesn't depend on what you sing, but how loud you sing it © Getty Images

Spread of COVID-19 doesn’t depend on what you sing, but how loud you sing it

Scientists say that singing generates similar amounts of aerosol droplets as speaking and the risks increase for both as volume increases.

Singing is no more risky than talking when its comes to the possibility of coronavirus transmission but it all depends on how loud a person is, scientists have said.

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In a new study, which is yet to be peer-reviewed, researchers at the University of Bristol have found that speaking and singing generate similar amounts of aerosol droplets when the sound volumes are the same.

They found that higher volume was associated with an increase in aerosol mass in both speaking and singing, with the loudest level generating up to 30 times more aerosol mass than the lowest volume.

However, they said there were no significant differences in aerosol production between genders or among different genres of music such as choral, musical theatre, opera, jazz, gospel rock or pop.

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Aerosols are the tiny particles of liquid and material that float around in the environment and can carry anything from smoke and dust particles to water and saliva.

Recent research has suggested that COVID-19 can be transmitted through aerosol particles, with the World Health Organisation (WHO) saying it could not rule out airborne transmission.

Singing was initially identified as a high-risk activity during the COVID-19 pandemic, with performing arts venues remaining closed even as lockdown measures were eased.

But last week, the government changed its guidance to say both professionals and non-professionals could engage in singing as of 15 August, provided the performers and audiences were following the guidelines on hygiene and social distancing – a decision that was informed by the study.

Our research has provided a rigorous scientific basis for COVID-19 recommendations for arts venues to operate safely by ensuring that spaces are appropriately ventilated
Jonathan Reid, University of Bristol

Culture Secretary Oliver Dowden said: “I know singing is an important passion and pastime for many people who I’m sure will join me in welcoming the findings of this important study.

“We have worked closely with medical experts throughout this crisis to develop our understanding of COVID-19, and we have now updated our guidance in light of these findings so people can get back to performing together safely.”

As part of an ongoing research project, called Perform, the researchers looked at the amounts of aerosols and droplets generated by a large group of 25 professional performers that were up to 20 micrometres (0.02m) in diameter.

The singers performed a range of exercises including breathing, speaking, coughing, and singing at a hospital operating theatre with a “zero aerosol” background.

Dr Florence Gregson, a researcher at the University of Bristol and first author on study, said using this hospital setting setting meant “any aerosol we detected with our measurements, we could directly attribute only to what the singer had produced”.

A scientific experiment to measure the spread of aerosols emitted when singing is conducted in an orthopaedic operating theatre, an environment of
A scientific experiment to measure the spread of aerosols emitted when singing is conducted in an orthopaedic operating theatre, an environment of “zero aerosol background” © Declan Costello

The experiments included singing and speaking Happy Birthday at different sound levels, between the ranges of 50–60 decibels (dB), 70-80 dB and 90-100 dB.

At the loudest level, singing generated more aerosol particles than speaking but the researchers said that this difference was “very modest”.

Based on their findings, the researchers said ensuring adequate ventilation in the venue may be more important than restricting a specific activity.

Jonathan Reid, an expert in aerosol science at the University of Bristol and a corresponding author on the paper, said: “The study has shown the transmission of viruses in small aerosol particles generated when someone sings or speaks are equally possible with both activities generating similar numbers of particles.

“Our research has provided a rigorous scientific basis for COVID-19 recommendations for arts venues to operate safely for both the performers and audience by ensuring that spaces are appropriately ventilated to reduce the risk of airborne transmission.”

The risks should not be played down because of this – we don’t want choir members getting infected and potentially dying from COVID-19 whilst doing what they love
Dr Julian Tang, University of Leicester

Dr Julian Tang, honorary associate professor in respiratory sciences at the University of Leicester, who was not involved in the study, said: “Also, the study was performed on individual singers one at a time – when the particle profile was found to be similar to talking. The risk is amplified when a group of singers are singing together, eg singing to an audience, whether in churches or concert halls or theatres.

“This may also affect the airflow dynamics of that air volume which may be more than the individual contributions from each singer via some complex resonant entrainment airflow dynamics that may propel these aerosols further. It is not comparable to the quiet breathing of the audience whose breathing will not be synchronised in a coordinated manner – like the exhalations of the choir – or talking to each other on a one-to-one basis.

“The risks should not be overly underestimated or played down because of this – we don’t want choir members getting infected and potentially dying from COVID-19 whilst doing what they love.”

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He added: “It is a nice study but not exactly representative of the real whole choir dynamic which really needs further study to truly assess the risk of such large volume synchronised singing vocalisations/exhalations.”

Q&A: What is the R number, and why is it relevant to coronavirus?

The reproduction number – often called the R value or R number – is a measure of a disease’s ability to spread. It tells us how many people a single infected person will pass on the disease to.

The R number for COVID-19 that’s being quoted in the media and government briefings is what’s known as the ‘effective’ reproduction number. This value can go up and down.

We can reduce R by making it harder for the disease to spread, by implementing measures such as social distancing, closing restaurants and non-essential shops, and encouraging people to stay at home.

Every disease also has what’s called a ‘basic’ reproduction number, R0, which is the fixed value of R if no measures are put in place. For example, measles is highly contagious, with a R0 as high as 18, while COVID-19 has a R0 of around three.

So if COVID-19 was allowed to spread through the population, an infected person would, on average, give the disease to three other people.

But if all these people are practising physical distancing, then the virus can’t spread so easily and the effective R value goes down.

The crucial thing is to keep R below 1. If we can do this, then the number of new cases dwindles and the outbreak will eventually come to a halt.

Conversely, if R rises above 1, then we run the risk of rapidly escalating case numbers that would require stronger measures to keep the virus under control.

Because of this, R is used by governments to assess how we are doing in our efforts to stop the spread of COVID-19, and to adjust our actions, if needed.

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