Students of the AGH University of Science and Technology in Kraków of the Laboratory of Technical Acoustics of the Department of Mechanics and Vibroacoustics have checked the influence of various types of face shields on the speech transmission index (STI).

The research, conducted by members of the Acoustic Engineering Faculty of Acoustics in the field of Acoustic Engineering: Michaela Murzyniec, Emilia Puchała and Kinga Sapieja, tested the influence of various types of face shields in an objective and subjective way. The most popular face shields were tested: a disposable mask, a two-layer smooth cotton mask, a two-layer cotton mask with overlaps, a medical mask, a single-layer neck warmer, a half-helmet and a helmet.

The results of the experiment show that the use of face shields does not improve speech understanding. Both the results of the measurements and the surveys conducted showed that, helmets have a negative impact on the quality of the received message.