School & District Management

Some Researchers Call for Classroom Sound Systems

By Christina A. Samuels — March 06, 2007 6 min read
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Classrooms can be noisy places. Any teacher who leaves work with a sore throat knows this, and research from audiologists and speech-language pathologists backs it up.

But because people can’t see noise—the rumble of trucks and cars outside a window, the whoosh of a heating and air-conditioning system, the squeak of chairs and desks sliding across tiled floors—eliminating noisy distractions gets short shrift when educators are thinking of ways to improve student performance, some researchers believe.

They suggest that classroom-amplification systems are needed for all students. In the most sophisticated of such systems, teachers wear microphones that project their voices to speakers strategically placed around their classrooms. These “soundfield” systems, usually about $1,000 a classroom, provide a smoother, louder sound with little reverberation and no feedback.

Other, less pricey systems are meant to be portable, with a speaker that can be moved from room to room.

Proponents of classroom amplification include Carol Flexer, a professor emeritus at the University of Akron, in Ohio. She has worked for years to convince educators that paying attention to noise in the classroom is just as important as paying attention to whether children can see the page in a textbook or not. No one would expect students to read if the lights were so dim they could barely make out the words on the page, she says.

“We expect to see fine detail. Why wouldn’t we expect to hear fine detail?” Ms. Flexer said. She has published several studies on the topic that are commonly cited by researchers, as well as by companies that sell such systems. She notes that young children are even more distractible than adults because brain neurology that allows for concentrated hearing isn’t fully developed until adolescence.

Hearing Subtle Differences

Joseph J. Smaldino, a professor of audiology at Northern Illinois University, in Dekalb, is also a supporter of such systems and a researcher in the topic.

“If you look at the literature, a lot of things are affected by classroom amplification—on-task behavior, speech intelligibility,” he said. “The problem with acoustics is, it’s not evident to people. If you had half the lights on in the classroom, everyone would complain.”

Koko Mikel, a 4th grade mathematics and science teacher in the Japanese-immersion program at Sand Lake Elementary School in Anchorage, Alaska, has used an amplification system for about three years. She said it works well for her because her voice is soft, and it helps her students “hear the very subtle sound differences” in the language they are learning.

Amplification Systems

Devices include teacher microphones, below, connected to speakers or portable systems.


The most sophisticated classroom-amplification systems are called “soundfield” systems. Teachers wear a microphone, above, around their necks that amplifies their voices through speakers placed in the classroom. Supporters of such systems say research shows they increase comprehension for all students, particularly the young, those with hearing loss, or those learning another language. The devices also reduce teachers’ vocal strain.

The Acoustical Society of America has said such devices can be useful, but should not be routinely installed in classrooms. It recommends architectural improvements such as using acoustical tiles on ceilings and walls, installing carpeting to reduce noise from sliding chairs and desks, installing partitions that extend from the ceiling to the floor, and shielding mechanical equipment or moving it away from classrooms.

SOURCES: Phonic Ear Inc., Education Week

“They really focus in on listening,” she said, “and their listening skills are very improved.”

Bill W. Tindall, the executive director of information systems for the 29,300-student Volusia County, Fla., district 40 miles north of Orlando, said his district is adding sound systems as it builds new schools or renovates old ones. Out of about 3,500 classrooms, he said, several hundred have the systems in place.

“We have about 80 percent of our users that feel that this is a very worthwhile investment,” he said.

Much of the research in classroom amplification has been conducted around how best to help students with hearing disorders, students learning another language, or students with disabilities.

The issue, audiologists say, is what they call the “signal-to-noise ratio.” The voice of the teacher, or anything the teacher wants the students to hear, is the signal. Anything else is noise.

Optimally, background-noise levels should not exceed 30 decibels, and the teacher’s voice should be at least 15 decibels louder than any background noise, according to recommendations from the American Speech-Language-Hearing Association, based in Bethesda, Md.

A 2006 study conducted by professors Stanley W.H. Leung and Bradley McPherson at the University of Hong Kong and published in the International Journal of Disability, Development and Education, measured the signal-to-noise ratio in classrooms and evaluated the teachers’ amplified and unamplified voices. The ambient noise in the urban classrooms was high enough for researchers to suggest that amplification systems may be needed.

In 2005, researchers at the same university looked at urban classrooms for the same publication, this time focusing on primary students. In their survey of 47 classrooms, Ching Yee Choi and Mr. McPherson found that the learning environment of many of the primary schools was not favorable for optimal classroom learning. In fact, teachers’ efforts to fight noise sometimes made things worse, according to the study.

“It was interesting to note that 25 classrooms used closed windows and air conditioning as a means to minimize the external noise, such as noise from a nearby road. However, the use of air conditioning for ventilation instead of open windows will generate a significant amount of internal noise for classrooms, especially when these wall-mounted units are malfunctioning,” the researchers noted.

Several studies in the United States have also examined the issue. One of the best-known was conducted in the 1980s and is referred to as the MARRS—Mainstream Amplification Resource Room—study. Funded by the U.S. Department of Education, its intended focus was to see if amplification could help children with mild hearing loss, such as during an ear infection.

The study results showed that most children, even those without hearing loss, appeared to benefit from amplification. Small studies conducted after the influential MARRS research tended to support that conclusion.

Good Design a Key

But some caution that amplification is not the only way to get a quiet classroom—good design is also necessary.

The Acoustical Society of America, an international scientific society based in Melville, N.Y., says amplification devices should not be used routinely in classrooms. First, they generally only improve teacher-to-student communications; student-to-teacher and student-to-student conversations remain unchanged with such systems if the students are not using microphones.

Also, if the classroom is poorly built in the first place, the devices could hurt more than they help. According to a position paper from the society, “Unless classroom walls, ceilings, and floors are acoustically upgraded to improve their sound insulation, amplified sound may be heard in adjacent classrooms, interfering with learning there.”

Room renovations can be of great help without requiring teacher training or the periodic maintenance required of amplification devices, the position paper continued.

Peggy B. Nelson, a member of the acoustical society and an associate professor of speech-language-hearing sciences at the University of Minnesota-Twin Cities, was the lead author on a 2005 study that examined groups of English-language learners in the 2nd grade. Students taught by unamplified teachers appeared to spend just as much time on task as students taught by amplified teachers.

The study did note, however, that English-language learners in noisier classrooms had a significantly harder time discerning the difference between words with a similar sound, such as “bat” and “bath,” and “boat” and “vote.”

So noise does matter, Ms. Nelson said. But there are other ways besides amplification systems to address the problem.

“You’ll find lots of enthusiasm for the systems, but they’re used inappropriately sometimes,” Ms. Nelson said. “They’ve been oversold a bit by anecdotal evidence.”

The acoustical society “is an advocate for schools’ being built right in the first place,” she added. “Soundfield systems are not going to be the whole solution.”

Coverage of education research is supported in part by a grant from the Spencer Foundation.
A version of this article appeared in the March 07, 2007 edition of Education Week as Some Researchers Call for Classroom Sound Systems


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