Sing softly and don’t shout to reduce the risk of Covid-19 spread, new research suggests, offering a ray of hope for musicians who have been restricted from performing in public.
Music makers have been hit hard by the coronavirus pandemic, with singing, as well as playing of woodwind and brass instruments deemed to be a potential high risk for spreading the disease – a concern fuelled by outbreaks in choirs.
As a result only professional rehearsals and outdoor performances have, until recently, been allowed in England, and even then only with a raft of precautions.
But the research offers hope to performers keen to get back on stage as soon as possible.
“It is not about the vocalisation – whether it’s singing or speaking – it is about the volume,” said Jonathan Reid, a professor of physical chemistry at the University of Bristol and a co-author of the research. “Just by singing a little bit more softly you really reduce the risk.”
In a study that has yet to be peer-reviewed, the team report how they asked 25 professional singers to breathe, speak, cough and sing into funnels. They then measured the mass of tiny droplets suspended in the air, known as aerosols, that were produced. The experiments were set up in an orthopaedic operating theatre, a setting chosen for its lack of background aerosols.
While one route by which Covid-19 spreads is via big droplets, largely produced when someone coughs and which fall to the ground within a couple of metres, Reid said aerosols were another possible route, noting such tiny droplets can linger in the air.
The team found the results of their study varied across participants, however at the lowest volume singing and speaking generated a similar mass of aerosols as breathing.
But when the team asked participants to recite Happy Birthday at different volumes, they found the loudest singing and speaking – 90-100dB – produced about 36 and 24 times the mass of aerosols respectively as generated by breathing.
“The volume of the activity, whether it is speaking or singing softly or speaking or singing loudly, that is really the main factor in governing the aerosol mass that is generated,” said Reid, adding that while singing generates a slightly higher mass of aerosols than speaking, at least when loud, the difference is very small compared with the effect of volume.
Co-author Declan Costello, an ear, nose and throat surgeon at Wexham Park hospital, noted other factors, including the size of the space and ventilation and duration of loud vocalisation, play an important role in potential infection risk.
In other words singing in a cathedral might pose a lower risk for spreading Covid-19 than shouting across a crowded pub. “Intuitively that would seem to be the case, assuming people are speaking or singing at the same sorts of volume,” said Costello.
However the research has limitations: it only measured aerosols produced by one individual at a time, while it did not look at how much virus was contained in the aerosol or the actual infection risk posed by the levels of aerosol produced.
“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,” said Dr Julian Tang, an honorary associate professor in respiratory sciences at the University of Leicester, who was not involved in the work.
The team say their findings have already contributed to new guidance for England released on 15 August by the Department for Digital, Culture, Media & Sport, which co-supported the study.
The 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.”
John Gilhooly, the artistic and executive director of Wigmore Hall in London, said the “music industry owes a massive debt to Declan Costello and his research colleagues who did all this work for no fee. It means we can begin to get larger chamber groups on stage and that we won’t have to lose the first six rows of audience seating.”
Alex Beard, the chief executive of the Royal Opera House, said the relaxing of social-distancing rules from 3 metres to 2 metres for singers and woodwind and brass players was “a big step forward” that would allow more players to perform together in the theatre’s pit when the company resumes live events with a socially distant audience this October.
