HUH? could you repeat that?

• By ROBBIN RITTNER-HEIR
• 08/01/04

If the quality of the acoustics in your classrooms make anything vocalized sound like you’re in an echo chamber, you then know that the most frequently-asked question ends up being, “Could you please repeat that? I couldn’t hear you.”

Those bouncing sounds also ricochet off cafeteria ceilings and walls, elevated by the clattering of serving trays, then migrate into and through the hallways. The level of noise rapidly approaches deafening.

It’s really not that anyone plans for the acoustics to function or, perhaps more accurately, malfunction as they’re inclined to do. Sometimes, it’s just the lack of planning. Music rooms and auditoriums are expected to make it sound as though you’re in the middle of Carnegie Hall (okay, that might be an exaggeration); however, those other learning areas, where good acoustics are important, often stand in need of a makeover.

Classrooms: Voice vs. Noise

“When you’re looking at (designing) musical facilities, an acoustical architect usually is hired,” says Kenneth Roy, senior principal research scientist for Armstrong Ceiling Systems . Yet, the American Institute of Architects does not require any acoustics design training as part of its curriculum, he adds. Classroom acoustics, particularly in older buildings, came almost as an afterthought.

In 2002, however, the American National Standards Institute (ANSI) adopted a new standard,“Acoustical Performance Criteria, Design Requirements and Guidelines for Schools.” While the primary thrust of the new standard was for students with temporary or long-term hearing impairments, improved acoustics have been shown to have a marked effect on learning for young children, those children who are learning English as a second language or those having learning disorders.

Christopher Brooks, owner of Orpheus Acoustics , says that achieving speech intelligibility in critical learning spaces is essential. That means increasing understandability, not just audibility, because, as Brooks says, speech may be audible, but that doesn’t necessarily mean you can understand what’s being said.

It’s about reducing noise produced by the HVAC or other mechanical systems, fluorescent ballast hum, external sound infiltration or prolonged sound reverberation time created by sound bouncing off reflective surfaces.

The Road to Intelligibility

Using good sound-absorbing materials can make a substantial difference in the ability to understand what’s being said. Classrooms are a primary focus. Ones with low ceilings require good, sound-absorptive ceiling panels since there usually is no carpeting, Roy explains. Rooms with tall ceilings, however, would need sound-absorbing materials on both the ceiling and walls, since sound can reverberate off both. “Ceiling tile is the cheapest way to put sound absorption in a classroom,” he says.

Cinder block walls often are a staple of classroom construction and will absorb a limited amount of sound, says Scott Tonkinson, director of marketing and advertising for Bonded Logic . Put several coats of paint on that cinder block and you further reduce its ability to absorb sound.

Bonded Logic produces environmentally friendly, natural material acoustic sound panels that can be applied to existing block walls, Tonkinson says. They can be flush mounted to the walls or attached with spacers to allow for additional sound dampening. These panels help to reduce echoing and diffuse sound.

Corridors are another problematic area, and Roy says you need to keep sound levels down so that the accompanying noise doesn’t filter into the classrooms. Because of their high-traffic nature, “durability is the key,” and he says that materials used in the hallways should provide about 50 to 60 percent sound absorption.

According to Roy, coaches like the idea of a gymnasium “rocking,” but forget that you still need to be able to hear. Though the gymnasium seldom is acoustically treated, controlling the overall volume of the noise, the reverberation time and resulting “slap echoes” requires some type of absorptive material on both the ceiling and walls.

Cafeterias present their own problems, and “keeping down the din” essentially is the working goal, Roy says. Acoustical ceiling panels and, in some cases, wall treatments are used to lessen the amount of sound reverberation.

Though providing the criteria for schools, Brooks contends that ANSI provides only a minimal standard for classroom acoustics and says that schools should strive for and put more dollars into even better acoustical design.

Spreading the Sound Around

While proper acoustical treatment of classrooms can make sounds more understandable to students, it doesn’t necessarily provide even sound distribution throughout the room. That, says Jeff Anderson, is where Audio Enhancement comes in.

Anderson, vice president of Audio Enhancement , explains that even though appropriate acoustical materials may be installed, sound audibility tends to drop off before it reaches the back of the classroom. “Even in most acoustically treated rooms, you can’t eliminate the distance from the teacher’s voice,” he says. So teachers and students are still left with the need to raise their voices to be heard.

Audio Enhancement’s system relies on microphone-transmitted sound amplification, with the sound delivered at a uniform level through ceiling-mounted speakers strategically placed throughout the room. This allows speech to be heard at a normal tone of voice, in spite of any existing background noise.

According to Anderson, the enhanced audio system is almost as simple to retrofit in a classroom as it is to do a new construction installation. Also, it is as economical as or more cost effective than other acoustical aids.