Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 May 21;382(21):2061-2063.
doi: 10.1056/NEJMc2007800. Epub 2020 Apr 15.

Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering

Philip Anfinrud  1 , Valentyn Stadnytskyi  1 , Christina E Bax  2 , Adriaan Bax  1
Affiliations

Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering

Philip Anfinrud et al. N Engl J Med. .
No abstract available

PubMed Disclaimer

Figures

Figure 1
Figure 1. Emission of Droplets While a Person Said “Stay Healthy.”
Droplets generated during speech produced flashes as they passed through the light sheet in this experiment. Panel A shows the flash count during each frame of a video produced at a rate of 60 frames per second, with and without a damp cloth covering the speaker’s mouth. Green indicates spoken words. The number of flashes was highest (arrow) when the “th” sound in the word “healthy” was pronounced. The trace offset below the graph shows that when the speaker’s mouth was covered with a damp cloth, there was no qualitative increase in the flash count during speech over the background level observed before the first trial of speech. The flash count during the silent periods between the spoken phrases remained above the background level, a finding that suggests that some of the speech droplets lingered inside the box for some seconds. Panel B shows frame 361 from the video, which corresponds to the red arrow in Panel A and to the highest number of speech droplets visualized in an individual frame of the video recording. The spots vary in brightness because of the differences in the size of the particles. Some of the spots are streaked, which suggests that the rate of 60 frames per second was insufficient to freeze the motion of the droplets. The feature highlighted by a dashed yellow circle corresponds to the tip of a very thin wire positioned just behind the light sheet; this wire provided a reference for setting the camera focus and gain before recording. (See the video, available at NEJM.org.)
See this image and copyright information in PMC

Comment in

References

    1. Duguid JP. The size and the duration of air-carriage of respiratory droplets and droplet-nuclei. J Hyg (Lond) 1946;44:471-479. - PMC - PubMed
    1. Marr LC, Tang JW, Van Mullekom J, Lakdawala SS. Mechanistic insights into the effect of humidity on airborne influenza virus survival, transmission and incidence. J R Soc Interface 2019;16(150). - PMC - PubMed
    1. Asadi S, Wexler AS, Cappa CD, Barreda S, Bouvier NM, Ristenpart WD. Aerosol emission and superemission during human speech increase with voice loudness. Sci Rep 2019;9:2348-2348. - PMC - PubMed
    1. Chao CYH, Wan MP, Morawska L, et al. Characterization of expiration air jets and droplet size distributions immediately at the mouth opening. J Aerosol Sci 2009;40:122-133. - PMC - PubMed