Comparison of aerosol emissions during specific speech tasks

TL;DR

This study investigates how different speech sounds influence aerosol emissions, revealing vowels produce more aerosols than consonants, which is crucial for understanding airborne disease transmission.

Contribution

It provides new insights into the relative aerosol emissions of specific speech sounds, highlighting mouth opening as a key factor in aerosolization during speech.

Findings

Vowels emit more aerosols than consonants.

Speech sounds significantly increase particulate counts over ambient levels.

Mouth opening influences aerosol production more than sound manner.

Abstract

The study of aerosols and droplets emitted from the oral cavity has become increasingly important throughout the COVID-19 pandemic. Studies show particulates emitted while speaking were generally much smaller compared to coughing or sneezing. However, recent investigations revealed that they are large enough to carry respiratory contagions. Although studies have shown that particulate emissions do indeed occur during speech, to date, there is little information about the relative contribution of different speech sounds in producing particle emissions. This study compares airborne aerosol generation in participants producing isolated speech sounds: fricative consonants, plosive consonants, and vowel sounds. While participants produced isolated speech tasks, a planar beam of laser light, a high-speed camera, and image software calculated the number of particulates detected overtime. This study compares airborne aerosols emitted by human participants at a distance of 2.54 cm between the laser sheet and the mouth and reveals statistically significant increases in particulate counts over ambient dust distribution for all speech sounds. Vowel sounds were statistically greater than consonants, suggesting that mouth opening, as opposed to place of vocal tract constriction or manner of sound production, might be the primary influence in the degree to which particulates become aerosolized during speech. Results of this research will inform boundary conditions for computation models of aerosolized particulates during speech.