ABSTRACT
Acoustical measurements and speech intelligibility tests were carried out to investigate the effects of masks on speech communication experienced in real Covid-secure university classrooms during the pandemic. Face-masked speech levels and noise levels were measured to understand the acoustical effects of masks on speech sounds during 15 multiple lectures in 3 university classrooms. The speech intelligibility scores were also evaluated for lower and higher SNR (signal-to-noise ratio) conditions, and for with and without the presence of visual information conditions to investigate the effects of both the acoustic and visual signals in understanding speech communication in actual classroom situations. In the 3 active university classrooms the students experienced on average: speech levels of 55.1 dBA (σ = 5.5 dBA), noise levels of 42.3 dBA (σ = 3.9 dBA), and a speech-to-noise ratio of 12.8 dBA σ = 5.2 dBA). The mean SNR values at the listener's position for the 15 lectures varied from 3.6 dBA to 20.0 dBA. The use of a portable sound amplification system increases the face-masked speech levels mostly at mid and high frequencies (500–4 kHz), thus it can be more useful for achieving higher SNR values in classrooms. The presence of visual cues have little effect on achieving more higher speech intelligibility scores in higher SNR conditions. The present results show that visual obstruction of the talker's mouth decreases speech intelligibility scores by a maximum of 10% in lower SNR conditions, particularly at a SNR of 6 dBA or lower. © 2023 Elsevier Ltd
ABSTRACT
At the start of the COVID-19 pandemic, multiple institutions mobilized to create recommendations that maximize indoor environmental quality to keep building occupants as safe as possible. Many of those recommendations were implemented in buildings across the world even before the presence of field data validated their effectiveness. However, as the pandemic raised awareness of the risks present in the air quality of everyday built environments, little is known about how occupants perceive these interventions or how they will perceive buildings when activities resume with an in-person requirement. This paper presents results from an online survey, conducted from April 23rd to May 8th, 2021, and offers a window into the perceptions of university students on a variety of physical intervention strategies that have been promoted for the return to classrooms. Our analysis explores differences in these perceptions between students from Colombia and the United States, where the vaccination rates of the population as of May 2021 differed substantially. An anonymous online survey was disseminated to students of higher academic institutions using images portraying 3D models of classrooms and written prompts to assess perceptions. Health risk and health promotion perceptions were evaluated using four categories: visual connection to the outdoors, occupant density, additional furnishings, ventilation system type, and number of operable windows. While the effectiveness of these strategies from an epidemiological standpoint was not considered, this survey aimed to measure the perceived effectiveness of these strategies as students prepare to return to in-person education in the classroom. Our analysis found a significant effect of different degrees of “connection to the outdoors” and “occupant density” on both perceived health risk and health promotion in both countries. Respondents ranked strategies like mask-wearing and natural ventilation as important interventions when considering a return to the classroom. Perceptions of health risk and health promotion between students taking classes in the United States and Colombia were significantly different regarding the presence of additional furnishings, and ventilation systems and number of windows in a classroom. The results presented here may shed light on how aspects of the built environment help shape perceptions of healthy environments during the pandemic. Copyright © 2021 Coronado, Rockcastle and Kwok.