Research finds singing in some languages could spread COVID-19 more easily than others

Tokyo — Ever since a chorale rehearsal in Washington state last March became a COVID-19 super-spreader event, sickening most of the singers and killing two, choir practice has been deemed high-risk, forcing many ensembles to forgo in-person practice and performances. 

But in Japan, most choirs have returned to practice rooms and concert halls, bolstered by studies here showing that with safeguards such as limiting rehearsals to 30 minutes, proper ventilation, masking and social distancing, viral hazards can be lowered substantially.

Analysis by Japan's Fugaku supercomputer shows that singing does spew about three times as many potentially coronavirus-laden particles into the air as talking, but Japanese researchers wanted more detail: Does singing in different languages create more potentially infectious droplets and aerosols? 

Modelling by Japan's Fugaku supercomputer shows the amount of particles expelled by a person speaking normally (left) and singing (right). Kobe University/RIKEN/Toyohashi University of Technology/Kyoto Institute of Technology

The answer, simply, is yes. At least three separate studies here have shown that when it comes to emitting droplets and aerosols, not all languages are equal.

Researchers were commissioned last December by the Japan Association of Classical Music Presenters, which represents professional musicians, orchestras and concert hall managers, to run an experiment involving un-masked singers. Eight professional vocalists — equally divided between male tenors and female sopranos — took turns performing short solos in a laboratory-clean room. The subjects sang excerpts from three pieces commonly performed here: A popular Japanese children's song; Beethoven's Ode to Joy; and Verdi's La Traviata. 

In terms of vocal emissions, it was no contest: Trilling in German and Italian generated twice as many particles per minute (1,302 and 1,166, respectively) as crooning in Japanese (580). 

But association director Toru Niwa cautioned that the takeaway from the research shouldn't be to avoid European music during the pandemic. While several amateur singing venues have yielded super-spreader incidents, Niwa said Japan's professional choirs haven't been tainted by a single community transmission event — regardless of the language being sung — despite returning to rehearsals and performances in live music halls. 

"Classical music is basically the western canon," he said. "If we stopped singing in French, Italian and German, we wouldn't be able to perform anymore." Indeed, the quirky annual Japanese rite of belting out the finale to Beethoven's Ninth Symphony throughout the month of December accounts for a major chunk of classical music revenues here.

Imagery from research commissioned by the Japan Choral Association shows, at left, the particles emitted by someone singing in Japanese, and, at right, those emitted by singing in German. Japan Choral Association

A separate experiment by the Japan Choral Association, which represents 4,500 amateur groups, had 20 child and adult singers perform solo excerpts, pitting a Japanese graduation tune against Beethoven's Ninth. The study found that singing in Japanese propelled particles a maximum distance of about 24 inches (61 cm) — only about half as far as warbling in German, which flung particles up to 44 inches (111 cm) from a singer's mouth.

"When singing in German, we advise our members to stand at the maximum distance from each other," said Masakazu Umeda, secretary-general of the choral association. 

Umeda and Niwa explained that their studies reflect how the Japanese language — with its soft, comparatively gently-voiced consonants — leaves a lighter footprint when it comes to vocal emissions. In fact, the Japan Choral Association found that singing in nonsense syllables composed entirely of the Japanese vowels "ah, ee, oo, eh, oh" yielded almost no emissions at all. 

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Guidance for school choirs from Japan's Ministry of Education directs children to wear masks and keep singers at least 6.5 feet apart, ideally in a "plaid" pattern, alternating positioning between rows, to make everyone more visible to an audience. 

Distancing singers on stage for pro ensembles means choirs must get by with just 60 singers, instead of the usual 100 or more. Opera singers have been advised not to face each other when performing, and not to walk around the stage mid-song.

An image from modelling done by Japan's Fugaku supercomputer shows the ideal "plaid" pattern spacing for members of a chorale group to avoid spreading the coronavirus, with an infected individual's orally expelled particles represented by the middle person in the model.  Kobe University/RIKEN/Toyohashi University of Technology/Kyoto Institute of Technology

Niwa said that by having singers stand in the alternating plaid pattern, with at least the recommended distance between them — whether they wear masks or not — "the risk is substantially reduced."   

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