Breaking the 'Sound Barrier' for Enhanced Classroom Learning
- By Christopher Lawton
- October 1st, 2008
The ability to hear properly, especially in pre-school and elementary school classrooms, is one of the most important factors in a child’s ability to process and learn new information. According to the Institute for Enhanced Classroom Learning, children in today’s classrooms have difficulty understanding 20 to 30 percent of what their teacher said because of excessive ambient background noise, reverberation, and a poor signal to noise ratio (SNR).
One of the biggest contributors to a classrooms’ ambient noise level has traditionally been a school’s HVAC system, regardless of whether it is roof mounted or wall mounted. Most HVAC systems currently on the market today operate at ambient noise levels that are considered to be too high for most classroom instruction. But what if a school’s HVAC system could be removed as a factor in ambient classroom noise levels?
In 2002, due to the increasing realization of the problem regarding classroom acoustics, the American Standards Institute (ANSI) along with the Acoustical Society of America (ASA) set out to create a lower overall ambient noise national standard for acoustics in the classroom. Their results became known as S12.60-2002 which set an acoustical standard of 35dBA for all background sound (ambient) levels. Unfortunately, while ANSI’s new standard was significant when it came to new construction, it did not take into effect relocatable classrooms which are harder to insulate and therefore can have more ambient noise, especially for older models still in operation.
Shortly after the 2002 ANSI standards were developed, several companies began to consider development of a new HVAC unit to try to meet the stricter ANSI acoustical standard. Although not a mandatory standard and therefore not enforceable, those companies became convinced that development of new equipment was both technologically possible and fulfilled a need that existed within the marketplace.
“Many in the industry thought that ANSI’s new standard would be nearly impossible to meet, especially with a vertical wall mounted unit,” said Irv Derks, vice president of engineering, Bard Manufacturing Company, Inc. The companies embarked in the development of an acoustically improved HVAC system with an ambient noise level of no more than 45dBA that would be more energy efficient and environmentally friendly. The unit had to not only worked well with new construction, but also be able to be easily retrofitted to older construction, including portable classroom units.
Lawrence Berkeley National Laboratory (LBNL) then became involved in a two-step testing process of a prototype unit. “Over a series of many months, LBNL compared the energy efficiency and the ventilation capability and did the acoustical comparisons to a standard wall mount in an actual portable classroom at their facility,” said Derks. What they found was that the new unit not only was more energy efficient but it also ventilated better.
From there, the team employed a field test program in which 10 prototype units were shipped and installed in two different California schools. Ultimately, the field tests backed up the original tests conducted by LBNL. However, still not completely satisfied with the acoustical improvements, the companies continued to develop additional enhancements which resulted in even more reductions in the ambient sound level.
While the field tests were wrapping up, they decided they needed to find out how the unit would function in a real-world portable classroom environment. They acquired and set up an older, portable classroom complete with desks and the other accoutrements found in a typical classroom. Then, they replaced the existing wall mounted HVAC unit with the test unit.
“We wanted to put in place an older classroom, like those developed around 1992, to demonstrate what the new unit could do in a practical application,” said Maury Tiernan, Geary Pacific’s Bard product manager. “The older classrooms are more typical of what’s in service at many schools and so we wanted to demonstrate how the unit would do when retrofitted to an older, existing classroom.”
Next, they brought in two of the original co-authors of the ANSI standard to conduct their own tests within the classroom and see how the unit performed acoustically.
Louis Sutherland, chief scientist and deputy director for the acoustic research group of Wylie Laboratories, also served as the co-chair of the large ANSI Working Group that wrote the Classroom Acoustics standard. “We took ambient sound level measurements at a number of selected positions before the air conditioning unit was turned on,” said Sutherland. “When they said, ‘okay, now it’s on’, I said ‘you’re kidding’. The unit was running and by my own hearing I couldn’t tell any difference between when it was on and when it was off.”
Sutherland’s more scientific tests essentially backed up what he heard, or in this case, didn’t hear. “When we reviewed our test results they showed that the lowest ambient noise level with the HVAC system turned off was about 33 dBA,” he said. “When we then turned on the HVAC system at three different power levels of operation, the noise levels ranged from 35 to 39 dBA.” What Sutherland quickly realized was that in most instances, the unit ultimately met the 2002 ANSI standard of 35 dBA.
Their success led them to convince Val Verde Unified School District in Perris, CA, to purchase a unit for their audiology lab that tests students for hearing disabilities.
According to the school’s audiologist, Randy Lerner, the environment for testing and evaluating students has improved by 20 percent do to a considerable reduction in ambient noise from 58 dBA to 37 dBA.
The ears of students across the U.S. and the teachers who work so hard to educate would probably most certainly agree.
Christopher Lawton is the author of more than 50 business and trade publication articles and case studies. He is the owner of wecreate, a Pittsburgh-based brand marketing communications firm that specializes in helping companies manage and enhance their brand image. Visit them at www.wecreatesolutions.com.