Low-Level Classroom Noise Distracts, Experts Say

Decisions reveal tricky balancing act

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It’s easy to understand why learning may suffer when the teacher’s voice has to compete with a passing 747, but emerging research suggests that quieter noises can have varied effects on student learning and memory.

“It doesn’t take very much sound to really be detrimental to the listeners,” said Gail M. Whitelaw, the director of the Ohio State University Speech-Language-Hearing Clinic in Columbus. “So much of school is auditory, oral learning, and one of the things we know is sound can create more issues with kids with anxiety and attention.”

Low or barely perceptible sound—be it from a lecture in the classroom next door, a heating system that keeps turning on and off, or even a classroom aquarium filter—can increase stress and interfere with memory and learning. Yet it is much less likely to come to the attention of teachers or the students themselves than aircraft or construction noises.

“You can’t depend on the kids to complain,” said Ruth M. Morgan, a speech pathologist at Ephesus Elementary School in Chapel Hill, N.C. “Kids generally go with the flow, and they wouldn’t let you know there’s too much background noise.”

How Loud Is Too Loud?

Noise is measured in decibels on a logarithmic scale; every 10 decibels marks an increase in sound that is twice as loud. Normal conversation is usually in the range of 60 to 65 decibels, and children often speak more softly than adults, as low as 35 decibels.


Federal and state guidelines generally recommend that schools dampen sustained sounds of about 90 decibels and above—the level of heavy freeway traffic, for example—which can cause hearing loss if students are exposed to it for extended periods. And federal and state transportation agencies often provide grants to help schools protect their buildings from regular, dangerously loud sounds like a 135-decibel jet takeoff.

Near Chicago’s O’Hare airport, for example, federal and local transportation agencies have spent $350 million to muffle sound at 124 schools, according to the O’Hare Noise Compatibility Commission, an intergovernmental agency in Chicago.

But noise in the background doesn’t have to be that loud to be distracting for students. In a 2013 study in the Journal of Urban Health, a publication of the New York Academy of Medicine, 8- and 9-year-old students who had higher “ambient” noise levels in school performed significantly worse on standardized tests in mathematics and French language, after controlling for their socioeconomic backgrounds. A difference of 10 decibels of regular background noise was associated with 5.5-point-lower scores on average in both subjects.

Similarly, a prior study found students were highly distracted by a television playing in an adjoining room, even when it was barely audible, but they were unable to identify why they were having trouble concentrating.

The results don’t surprise Ms. Morgan in Chapel Hill. She noticed that while the classroom didn’t seem particularly loud, both she and her students seemed to be having trouble following conversations during sessions in which students worked in groups.

“So much of class now is the children speaking to each other, doing buddy reading,” she said. “And children’s voices are softer; I was having difficulty hearing them.”

Some sounds are also more vulnerable to distortion: s-, sh-, and ch- sounds in speech are particularly easy to mistake when competing with low-frequency mechanical sounds, such as the hum of a computer fan or heating system.

Ms. Morgan said she thinks her school’s noise issues may be common in older schools, where former “open concept” classrooms were later closed in with walls that typically have less noise insulation than new construction, allowing students to hear more lectures and mechanical sounds in other rooms.

Ms. Morgan downloaded a measuring application for her iPad and checked her room and seven others throughout the building, finding background noise levels of around 60 decibels, just loud enough to compete with conversation. The district eventually paid $1,000 per classroom in the school to install sound systems and to outfit teachers with microphones.

“It does add up; it’s kind of expensive, but in the end it’s worth it in terms of student learning,” she said.

Ms. Whitelaw said many schools adopt “solutions” that actually make noise distractions worse, such as adding tennis balls to the legs of desks to change a squeaking sound to a scratching sound when students move. The second sound may be quieter but more annoying.

“We know that noise is really distracting to kids’ attention, and affects kids’ stress levels,” Ms. Whitelaw said.

Repeated studies have found low-volume but chronic ambient noise raises cortisol, a chemical marker of stress, in both children and adults, but younger children are especially sensitive to it. Moreover, intermittent sounds, like a machine that turns on and off throughout the day, can have a stronger effect.

“When kids have high anxiety, and we are adding noise in the classroom, they are struggling to follow the teacher and they are getting exhausted by the end of the day,” Ms. Whitelaw said. “We know that’s a big factor in student performance.”

Noise and Attention

However, some studies are beginning to temper the thought that noise distraction is always bad.

In a study in the spring 2014 Journal of Applied Research in Memory and Cognition, which was discussed at the annual Society for Neuroscience conference in Washington in November, Swedish students were asked to learn texts in either an easy or difficult font, and in either a quiet classroom or one with low background speech—considered one of the most distracting types of sound. Students who had easy-to-read text had more difficulty remembering it when they had learned in a classroom with background speech, but students recalled more of the hard-to-read text when they were also coping with more ambient noise.

“A lot of it is the content of the noise” in comparison to what the student is doing, Ms. Whitelaw said. “If someone is having a conversation behind you, it’s more distracting if the teacher is lecturing, and you find it boring.”

Researchers suggested the students were more aware of the need to concentrate because the text seemed more difficult, and so were better able to “block out” the distractions.

Not every class can be outfitted with microphones or buffered with audio tiles, but Gary William Evans, a professor of human ecology at Cornell University, in Ithaca, N.Y., suggested in the Annual Review of Psychology that it is important for educators and students to be aware of how different noises will affect different types of students.

For example, in a study in the November issue of PLOS-One, researchers at the University of Southampton in England assigned five different tests of working memory—including word recall and recognition tasks, and a game in which students had to push a button or hold back in response to a cue—to 8- to 10-year-old students who had been rated by teachers as having low, normal, or high levels of attentiveness. The students performed the tasks in either a room with a quiet background or one with white noise of varying volumes, from 65 to 85 decibels.

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The better that students were initially at paying attention, the worse they were affected by white noise at any level. By contrast, researchers found students with poor attention skills benefited from the additional noise, perhaps for the same reason sounds had helped students in the other survey remember text in a difficult font: The challenge may have sharpened their focus.

“Even if we have to say certain kids have to be in certain environments ... the important thing is to know what the environment is: Make a measurement, just so you know what you are starting with,” Ms. Whitelaw said.

“A lot of things teachers think are good can be problems,” Ms. Whitelaw said. “We have teachers say, ‘I put music on to calm kids,’ but I’ve been in classrooms where they have music on pretty much throughout the day, even when there is lecturing, and it really contributes to the ambient noise. We’ve heard music is good, well, but let’s look at the sounds overall.”

Vol. 34, Issue 15, Pages 1, 16

Published in Print: January 7, 2015, as In Class, Soft Noises Found to Distract
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