As Australia’s public institutions slowly return to normalcy in the tail end of the COVID-19 pandemic (or brace for further waves, depending on where you are), researchers are beginning to see some of the lingering issues with pandemic safety measures. While these measures are in place to maintain public health and prevent infections, one often overlooked place where masks, increased need for ventilation, and a subsequently more complex auditory environment is having a significant impact is in the classroom. Before COVID, classrooms were already a less-than-ideal acoustic environment, with background noise and poor acoustics causing experts concern about learning outcomes. Post-COVID, teachers are only struggling more. So what can be done? Let’s explore.
Masks, Ventilation, and Speech
While masks are incredibly effective at reducing transmission of dangerous airborne particles, one unfortunate side effect is that they also muffle sound and block visual speech cues. This makes the auditory environment of a classroom harder on students already living with hearing or attention difficulties, and more typical students will also require higher investments of focus in order to maintain their same levels of academic performance.
Researchers at the University of Illinois’ Augmented Listening Laboratory (ALL) measured the effects of a number of different styles of mask on both the sound quality and visual reception of speech. Their findings showed that overall, all masks degraded sound quality to an extent, with thinner cloth masks (including the medical-grade N95) only mildly lowering high frequencies, and plastic masks and face shields completely reflecting sounds away from the listener. On the other hand, cloth masks were rated worst for visual reception, with clear plastic “windowed” masks and face shields being the obvious winners due to their ability to show the speaker’s mouth, which aids the listener’s speech recognition despite the poor audio quality.
The key finding of the ALL’s research was that masks of all types only block sound from moving forward – sound was still easily heard from the sides, above, and below the speaker. This meant that the sound quality of lapel microphones was almost completely unaffected by the speaker’s mask – more on that in a minute.
Another, more infrastructural public health measure introduced into schools since the beginning of the pandemic was an overhaul of ventilation systems. Many states released guidelines on how schools should alter their processes to increase airflow and air quality for students, including moving classes outside, updating and cleaning air conditioning systems, and some states even provided schools with air purification systems to be installed in high-traffic areas. Much like masks, these measures were great for helping constrain the spread of COVID-19 among students and staff, but tough on the learning environment.
There is one piece of sound technology that has been around since the 1980s which has proven to be a perfect solution for the issues raised by COVID safety measures in classrooms: sound field systems. This is a simple system whereby the teacher’s voice is picked up by a lapel or headset microphone and transmitted either to a speaker in the classroom or directly to a student’s hearing aid (this second configuration is also sometimes called a FM or HAT system). These were originally developed to help students with auditory issues better understand teachers, but have been proven to benefit all students with engagement, attention, and even improved reading skills.
While some schools have utilised sound field systems for decades to assist students with hearing difficulties, they are also the perfect solution to the problems presented by the necessities of masks and ventilation during the pandemic. The sound quality of lapel microphones is completely unaffected by masks of any kind, including the plastic “windowed” masks which rated worst for sound in the ALL’s research.
An additional consequence of the current need for masks that sound field systems help assuage is vocal strain and fatigue in teachers. With just a mask, teachers need to speak louder than normal to be heard – add in traffic and weather when teaching outside, air conditioning or purifiers when teaching inside, and the lack of visual speech cues, and many teachers have suffered real health issues while trying to teach effectively. Sound field systems mean that teachers can speak at a comfortable level and, if students are still having trouble hearing, additional speakers (at an appropriate volume) can be placed around the classroom to create a more balanced sound field.
The pandemic has presented our societies with a number of challenges in areas we couldn’t have anticipated, and addressing those effectively has taken time. Noise is one of the most immediately stress-inducing forms of environmental pollution we face, and the pandemic drastically altered soundscapes in a wide variety of environments – some for the better, and some, like classrooms, for the worse. But nuanced research and technological application can lead to not just overcoming these problems, but adapting to them in ways that actually improve quality of life for those affected.
To learn more about how noise is affecting our daily lives, head over to https://www.noisenet.com/.