By Dorothy Wigmore
How does noise affect us?
Like stress, loud noise increases blood pressure, leading to heart-related problems. It also can cause endocrine disruption (another route to cardiovascular effects) and gastrointestinal effects.
People get frustrated or anxious around noise (e.g., reactions to fire crackers, blaring music). Muscles tense, breathing changes and heartbeats increase—all common stress responses.
Different body tissues resonate at really low noise levels (e.g., loud, thumping bass music), causing headaches, nausea, ear problems, dizziness and more.
Noisy environments present safety hazards, such as not hearing warning sounds, and decrease concentration. Students learn less in noisy spaces.
Noise also interferes with our ability to hear, often forcing school staff to shout or yell. The strain leads to voice disorders, sometimes called “teacher’s voice.” They range from laryngitis to a huskier voice to nodules in the larynx. A 2016 study of 14,256 Miami teachers found absenteeism costs from voice disorders were about $1 million.
Finally, there’s temporary or permanent hearing loss and tinnitus (ringing in the ears), with a variety of consequences.
What else should we know about noise?
Sound is vibration passing through something—air, water, surfaces.
Frequencies (pitch) matter. With good ears, we generally hear sounds between 20 and 20,000 hertz (cycles/second). Hearing loss and resonance vary by frequency.
Distance and time also matter. The closer we are to a noise, and the longer there, the worse the effect.
In schools, there also is resonance and background noise from ventilation systems.
“In one workplace, people said they were dizzy, had ear problems, felt like they were losing consciousness, but never actually did,” says Canadian occupational hygienist John Oudyk.
“We checked out all the air quality issues,” he explains. “Nothing showed up. Then we used the noise meter, looking at the frequencies. I think at 60 hertz, we had 87 decibels. It wasn’t noise you would perceive but you could feel it in your head … If you have a lower frequency, then you’ll feel it in your thorax, depending on your size.”
What are decibels? How are they used?
Anything above 65 decibels (dB) eventually wears down our hearing. Regular exposure to noise at 80 to 85 dB can cause legal deafness.
What’s a decibel? Basically, it’s sound measured on a logarithmic scale. (You can’t just add or subtract numbers.) Sound level meters and the law use the dB(A) scale to account for how people hear.
New Jersey’s Public Employees Occupational Safety and Health (PEOSH) uses federal OSHA noise rules. When employees may be exposed to more than a time-weighted eight-hour average of 85 dB, employers must have noise monitoring and free hearing/audiometric testing programs. They also must try to reduce the noise. Engineering changes are much more effective than hearing protection, which must fit and account for the frequencies and sound levels.
The law also limits how long to be in noisy places, based on the sound level doubling every five dB. That means four hours at 95 dB(A). Most authorities elsewhere use a three dB doubling rule; that’s just under an hour at 95.
The law ignores other effects, while U.S. classroom acoustics standards limit background noise to between 35 and 40 dB(A) and ventilation background noise to similar levels.
Those Paterson School District air purifiers were rated at 45 and 55 dB for low to high speeds. Their Carrier OptiClean air scrubbers are between 51 and 56 or 61 and 64 (depending on the model). In reality, they’re likely worse.
No wonder Baker’s class had problems. To hear, we need a difference of 15 decibels between background noise and how loud the speaker’s words are when they reach us.
“If a student’s at the back to the room near (the unit) and the teacher’s at the front, to project their voice at almost 80 decibels to the back of the room, they’ve gotta be yelling,” Oudyk says.
Dorothy Wigmore is a long-time health and safety specialist and WEC consultant. She has worked in Canada, the U.S. and Mozambique, focusing on prevention and worker participation to solve job-related hazards. These days, she is writing Transmission Truth? a book about workers’ experiences in the pandemic.
What to do?
When school staff complain about noise, outside consultants often say there’s no problem if it’s less than 85 dB.
“They get these blinders on,” Oudyk says. “They’re ignoring real hazards that affect staff and the quality of education.”
Health and safety committees can:
- Survey members about the noise and its effects.
- Map noise (including from ventilation) in workplace inspections/walk-throughs.
- Use apps to measure noise at different frequencies (see resources).
- Push back about noise effects below 85 dB.
- Promote district purchase of personal microphone headsets and voice coaching to prevent “teacher’s voice.”
- Get agreements with districts about maximum sound levels for new equipment/tools and ventilation (including air filters).
“Occupational voice loss”
“Five steps to doing something about noise”
“Reducing noise in schools”
“Occupational noise exposure and controls”
“Occupational Noise Exposure Standard”
Standards – ANSI S12.60-2002
“Acoustical performance criteria, design requirements and guidelines for schools” (summary)
“Big city noise pollution is harming our health”