Sound Advice on Classroom Acoustics

When the Acoustical Society of America’s (ASA) new standards for educational classrooms were upheld on February 28, 2002, the celebration marked the end of five years of concentrated efforts. In 1997, professionals from HVAC, facilities planning, acoustical engineering and architecture industries; school audiologists; school administrators and educators; professors; and even lay people whose children struggle with hearing handicaps gathered to begin translating the research data into a workable construction blueprint. A total of 56 volunteers contributed to the final product.

Although the resulting document was written for K-12 classrooms, college input had its impact. One professor writes that, at his school, you could hardly make the students hear you — and, if they got the wrong idea or got off on the wrong track, they weren’t really learning. So, as ASA’s Standards Manager Susan Blaeser stresses, universities want to sit up and pay attention to this new construction wave as well.

CP&M: What prompted these new standards? What gaps were you trying to fix?

Blaeser: It came up as a result of increased concern among educators and acousticians that the sound level in classrooms was making it hard for children to learn. And when a topic becomes popular, scientists start doing research on it, they present papers and that research generates more research.

Naturally, people started to say there really should be a standard. This is typical because standards usually follow research. Experts in a given field try to gather the knowledge they have in the literature and best practices and bring it down to something people can employ in many circumstances. We all use standards, but we may not know it. When you buy a can of oil weighted W40, it’s graded according to a standard. Film is rated as ASA 400.

CP&M: So this is a new document, not a revision?

Blaeser: This is the first standards specifically for classroom acoustics, although the levels recommended have been around for many years. Actually, we went back in books written in the ’50s, so this is not new knowledge. But, the problem is, we’ve become more modern. In older times, schools were inherently quieter. There was less noise from air conditioning and heating systems, less traffic going by and there were fewer planes overhead.

Nor is it exclusive. The limits and levels we recommend are the same as those the World Health Organization recommends.

CP&M: Studies you cite show a difference between children’s hearing and adults’. How does that impact colleges’ decisions to follow the guidelines?

Blaeser: Actually there is a discussion of reverberation control for larger university classrooms in the standards, but it’s an annex. We have people working on that aspect.

But the need to be able to hear to learn is the core of most learning. A room with an echo makes it hard to listen if you’re age four or 40. Have you ever gone to a meeting in a hotel where the air conditioner is so loud nobody can hear the speaker? If that’s going on in your college classroom, your students are being short changed of their opportunity to learn.

Young children can miss as much as one word in every four. That means 25 percent of what the teacher says goes right out the window. And we’re talking in terms of normal hearing children, not kids with a stuffy ear from a head cold. Now, adults do learn to fill in a certain amount — if you didn’t hear every word you figure out what’s said from the context. Surely college students fall into that category but, if they’re taking something that’s new and challenging, they may not have the context.

You’re spending the money for the design of the building in the first place, so take the extra step to ensure the rooms don’t have an echo.

CP&M: Can manufacturers deliver these standards today?

Blaeser: It’s not a problem. All the materials are available — the acoustical ceiling tiles, paneling and other materials. Certainly, if there’s a demand for this, then there will be even more materials available.

If you are interested in a copy of the standards, the price is $35 at the Standards Store link: http://asa.aip.org>.

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