WMU News

Classroom amplification boosts learning

Aug. 9, 1999

KALAMAZOO -- Anyone who's ever been in an elementary school knows that classrooms can be noisy. And if you consider the number of children who have ear infections or other ear problems, it's easy to see how hearing what the teacher is saying can become a problem. But advances in technology offer a simple solution: amplify the teacher's voice.

Recent research suggests this can be very effective, says Dr. Nickola W. Nelson, a WMU professor of speech pathology and audiology. Nelson's study found that on a given day, as many as 40 percent of children could be suffering moderate hearing loss because illness.

"With their hearing fluctuating like that, it helps if the teacher's voice is at an equal volume from the front of the classroom to the back of the classroom," Nelson says.

Called sound field amplification, the practice calls for teachers to wear a small lapel microphone. The teacher's voice is then amplified to about 15 decibels and projected from speakers either in the ceiling or placed around the room at ear level.

"If a child is at the back, they might be hearing the teacher's voice out of the speaker even though the teacher is 20 feet away, improving the signal-to-noise ratio, with the signal being the teacher's voice," Nelson says.

In some unamplified rooms Nelson studied, the signal-to-noise ratio was zero, meaning background noise was as loud as the teacher's voice.

"If kids can hear sounds clearly, they have a greater ability to learn to read and write," Nelson says. "I had one teacher say that it used to take six weeks for the kids to know how to pronounce her name correctly. With sound field amplification, they do that within one week."

Media contact: Mark Schwerin, 616 387-8400, mark.schwerin@wmich.edu

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