The steady hum of school heating systems and air-conditioners can mean lower test scores for many young students, found a new study.
The finding adds to growing evidence that classroom noises interfere with learning. Despite an endless list of budgetary pressures, schools might want to put quiet at the top of their to-do lists.
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"The technology is definitely there," said Lauren Ronsse, a research engineer at the U.S. Army Engineer Research and Development Center in Champaign, Ill. "It's just a matter of schools placing priority on really designing and implementing HVAC systems with lower noise levels."
Plenty of studies have demonstrated the distracting power of noise in the classroom, said Peggy Nelson, a hearing scientist at the University of Minnesota, Twin Cities. In louder rooms, she said, kids have more trouble hearing the teacher and become easily distracted, even when they are reading to themselves.
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Schools near airports also report lower test scores than schools that don’t contend with airplane noise. In one study, German students started scoring better on reading and vocabulary tests after a nearby airport shut down.
Ronsse was interested in less obvious sounds like the general whirring of basic mechanical systems. In a paper last year, she and colleagues measured the volume in empty second-grade and fourth-grade classrooms in 58 classrooms in an Iowa school district. When they averaged each class's test scores, they found that kids who spent all day in louder classrooms tended to score lower on standard reading comprehension tests.
To follow up, the researchers collected similar data from 67 classrooms in 13 Nebraska public schools. There was a lot of variation in results, Ronsse reported this week at a meeting of the Acoustical Society of America in San Diego.
In general, though, fifth-grade reading scores were lower if students sat in rooms with more background noise. There was no such relationship in third-grade classrooms. And math scores didn’t vary with noise levels, possibly because teachers use more visuals when they’re teaching math than when they’re teaching words.
Guidelines set by the American National Standards Institute recommend that classrooms not exceed a background noise level of 35 decibels, which is the volume of a voice whispering from a distance of 15.
In empty Iowa classrooms, though, Ronsse measured levels ranging from 36 to 50 dB. In Nebraska, background levels ranged from 28 to 62. That’s creeping close to the sound of a roaring highway from 50 feet away.
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Lots of background noise sets kids up for problems, Nelson said. Studies have shown that kids make more noise in louder rooms. Surrounded by the scraping of chairs, the hum of the heating system, and the voices of other kids competing to be heard, some students may have a particularly hard time hearing what the teacher is saying.
And it's not that they're goofing off or using noise as an excuse, Nelson added. Young brains have a much harder time filtering a signal from the background than mature, adult brains do.
Along with previous work, she said, the new findings suggest the need for enforcement of ANSI's standards. At the very least, schools might want to work harder to meet them.
"People debate about whether these standards should be advisory or mandatory because, after all, schools don't have a lot of money," she said. "If it costs one or two percent more to build to quieter standards, I think this evidence says yeah, then raise the cost by one or two percent. It's worth it in the end because learning is more effective."