Some COVID-19 research with a linguistic angle

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Researchers looking at infectious disease transmission found that loud speech is more of a problem than coughing and sneezing, and this was true regardless of the language spoken (English, Spanish, Mandarin, or Arabic).

Aerosol emission and superemission during human speech increase with voice loudness

    Sima Asadi, Anthony S. Wexler, Christopher D. Cappa, Santiago Barreda, Nicole M. Bouvier & William D. Ristenpart

Nature, Scientific Reports, volume 9, Article number: 2348 (2019)

With 5 charts


Mechanistic hypotheses about airborne infectious disease transmission have traditionally emphasized the role of coughing and sneezing, which are dramatic expiratory events that yield both easily visible droplets and large quantities of particles too small to see by eye. Nonetheless, it has long been known that normal speech also yields large quantities of particles that are too small to see by eye, but are large enough to carry a variety of communicable respiratory pathogens. Here we show that the rate of particle emission during normal human speech is positively correlated with the loudness (amplitude) of vocalization, ranging from approximately 1 to 50 particles per second (0.06 to 3 particles per cm3) for low to high amplitudes, regardless of the language spoken (English, Spanish, Mandarin, or Arabic). Furthermore, a small fraction of individuals behaves as “speech superemitters,” consistently releasing an order of magnitude more particles than their peers. Our data demonstrate that the phenomenon of speech superemission cannot be fully explained either by the phonic structures or the amplitude of the speech. These results suggest that other unknown physiological factors, varying dramatically among individuals, could affect the probability of respiratory infectious disease transmission, and also help explain the existence of superspreaders who are disproportionately responsible for outbreaks of airborne infectious disease.

Lesson:  Speak softly; keep it down.


Selected readings

[Thanks to Amy de Buitléir]


  1. Chiara Maqueda said,

    September 10, 2020 @ 8:03 pm

    Another reason to dislike loudmouths …

  2. David C. said,

    September 10, 2020 @ 9:06 pm

    Wasn't it on the Language Log that someone shared a link to a snippet from a Japanese TV show claiming that speaking English is more likely to spread the virus because of the use of aspirated consonant sounds?

  3. David U said,

    September 10, 2020 @ 9:47 pm

    And people tend to talk louder in noisy crowded places like bars and parties…

  4. Peter Taylor said,

    September 11, 2020 @ 5:32 am

    @David C., Rire la Rémumligne! is also related.

    (I was inspired by that to try spreading my own Spanish version, but it doesn't seem to have got very far).

  5. Rose Eneri said,

    September 11, 2020 @ 10:51 am

    According to the "“fluid-film burst” mechanism hypothesis discussed in the article, "when the vocal folds come into contact during adduction, fluid films that form between them can then rupture during their subsequent abduction." It is the droplets formed by the bursting fluid-film that are expelled through the mouth thereby dispersing infectious agents.

    Under this hypothesis, it would still seem to me that speaking a language that makes more frequent use of laryngeal consonants would emit more droplets.

    I'd like to see more research into why some speakers were "super emitters."

  6. KeithB said,

    September 11, 2020 @ 11:46 am

    I think most of Mel Blanc's characters would have been super emitters: "Sufferin' Succotash!"

  7. Victor Mair said,

    September 11, 2020 @ 5:01 pm

    About 25 years ago, I had a grad student from Shanghai who spoke with a lot of strongly pronounced gutturals, even for such a common expression as hěn hǎo 很好 ("[very] good; well"). Long before COVID days, I always stood back a few extra feet from him when he spoke, wary of accidental expectoration. I've had acquaintances from other parts of China who spoke the same way.

  8. Victor Mair said,

    September 11, 2020 @ 5:08 pm

    I'm not going to name his name, but I once witnessed an amazing lecture by a famous Chinese professor who was talking about Zen-like elements in the Dream of the Red Chamber. He was extremely animated, and delivered his speech almost as though he were a possessed shaman. The people in the front row of the audience, who were about 10 feet away from him, had to duck from time to time to avoid the flying sputum.

    When the lecture was over, the speaker collapsed into his seat, with a white circle of foam and flecks around his mouth.

    An incredible performance!

  9. Dr. Emilio Lizardo said,

    September 12, 2020 @ 6:55 am

    Here's another likely Super Spreader (NSFW):
    The Honourable Sir Les Patterson

  10. Christian Weisgerber said,

    September 12, 2020 @ 12:51 pm

    @David C.

    Wasn't it on the Language Log that someone shared a link to a snippet from a Japanese TV show claiming that speaking English is more likely to spread the virus because of the use of aspirated consonant sounds?

    The followup to the cited paper, by the same researchers, actually finds that "voiced plosives" have a higher emission rate than "voiceless plosives". Since they tested English speakers with words like "tata", aspiration should be significantly correlated with voicelessness in their results.

    "Effect of voicing and articulation manner on aerosol particle emission during human speech"

  11. David C. said,

    September 14, 2020 @ 6:30 pm

    @Peter Taylor, Christian Weisgerber

    Thank you both for the links. Interesting that in the study the greatest contrast is found between vowels and consonants. The study cites the earlier paper from Inouye and Sugihara, which found weaker wind pressure and puff strength from speakers of Japanese, compared to speakers of English and Chinese. Better keep those masks on then…

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