Facilities (Walls, Ceilings & Floors)

The Noisy Classroom

How walls, ceilings and everything in between impact the way children hear.

• By Sarat Pratapchandran
• 09/01/19

Millions of children leave school “having simply not heard much of their education,” according to global sound and communications expert Julian Treasure.

“We are watering a garden and missing the flowers,” he said.

Hearing impairment affects one in six students once you add those with ear infections and other temporary illnesses. And, the built environment, especially walls, ceilings and everything in between impact the way children hear.

According to Regina Zappi, Au.D., CC-A, Associate Director, Audiology Professional Practices at the American Speech-Language-Hearing Association (ASHA), “hearing and understanding are important parts of the learning process.”

The Impact on Learning

Poor classroom acoustics impact how a student understands speech, reads and spells, behaves in the classroom and concentrates in class.

A 2004 study led by Donald Jamieson at the University of Western Ontario found that “the youngest children in the school system, whose classrooms also tend to be among the noisiest, are the most susceptible to the effects of noise.” Their auditory abilities are still developing.

“Every six feet, the sound of a teacher’s voice is going to decrease by three decibels,” said James Wright, western territory manager for acoustic panel manufacturer Primacoustic. By the time the teacher’s words reach children in the back row, it’s down significantly in volume.

The ambient noise from the built environment, including HVAC noise, the basic structural noise of the building, traffic, etc., also impact the way children hear. When children start shifting seats and moving their desks, this competes with the teacher’s voice.

Architects and acoustic experts cite reverberation, commonly known as reverb, as an important aspect of sound that impacts learners. “Reverberation is the persistence of sound and reverberation time is measured in decimals of seconds. This is the time it takes for a sound to decay 60dB and varies with frequency,” said Jason Lembke, AIA, principal at DLR Group.

According to Lembke, U.S. and European standards for reverberation times (RT) in classrooms differ, and “generally, a reverberation time range between 0.4 seconds and 0.8 seconds is desirable for schools.”

However, classrooms with an RT of over one second are not conducive for an ideal learning space.

“The ideal is 0.5 seconds,” sound and communications expert Treasure said.

Construction Materials

In the built environment, “absorptive materials do not isolate sound well, while sound isolating materials do not absorb sound well,” said Lembke.

Today, gypsum wallboard (gyp) and concrete masonry units (CMU) are primarily used in classroom wall construction. Ceilings can be exposed to the building’s structure, suspended tile products (pressed fibers, gypsum, fiberglass) or even wood.

According to Lembke, spaces needing an exposed structure should add acoustic materials (boards, sprays, etc.) to improve the performance of the space. The use of resilient flooring (VCT, LVT, ceramic tile, rubber, etc.) or softer carpet products is recommended. They all differ in costs, lifecycle and performance and should be analyzed to find out how they impact the learning environment.

The classroom is filled with hard surfaces. They reflect sound reaching the student’s ears at delayed times.

“Sound travels at about one foot per millisecond. So, if you’ve got a 30 foot long classroom, that’s a 30 millisecond delay,” said Wright. “This makes it difficult for the brain to process sound coming at you four or five times at four or five different timing intervals.”

School audiovisual suppliers or administration officials will recommend voice assist technologies to address the problem. “There is no real benefit to the amplification systems unless you do something to the room to actually address the acoustics issues first.”

Wright advocates using acoustic treatment in classrooms, as it will “bring the room noise level down to an area where a teacher can use their natural speaking voice.

Distractions

Bare walls and high ceilings contribute to poor listening and we live in an age where there is a premium on careful listening. According to Treasure, screens and keyboards dominate our communication and technology demands our constant attention.

“Children are simply not developing the habit of paying total attention to another person speaking,” he adds.

Poor acoustics in the built environment can impact teachers as well. “Average noise levels in German schools have been measured at 65 dB, which may not damage hearing but does increase the risk of heart attack with long exposure — so teachers may be shortening their lives by working in such environments,” said Treasure.

Today, one in three of a teacher’s sick days are a direct result of voice burnout as they have to talk too loudly to reach students. “We talk at 60 decibels, give or take, as our basis for speaking. If your basic room volume, with ambient noise and all, is already at 60dB, all of a sudden a teacher is using a raised voice for four, five, six hours a day just to be heard over the natural sounds of the room,” added Wright.

Design Solutions

However, innovative design solutions like “the operability and flexibility in wall positioning can dramatically impact the acoustic performance of a space,” said DLR Group’s Lembke.

An example is the Dickinson Middle School in Dickinson, North Dakota. With high mobility rates — 40 percent of students move in or out during the school year — teaming and community-building were a priority.

“Three of the four walls in the classrooms can be shifted or opened and [have] been designed for maximum agility. Classrooms can be merged, shifted and opened to adjacent areas,” Lembke said. Groups from four to fifty are supported, and conference space can be created just by moving walls and accessed from hallways without acoustically impacting the classrooms.

This built solution allows teachers to collaborate effectively and for students to seize opportunities academically, as well as personally with their peers.

Materials Solutions

Another solution, Armstrong’s Total Acoustics ceilings, “do two things at once: They absorb sound instead of reflecting it back, and they also block unwanted noise from adjacent spaces, making classrooms quieter and more comfortable,” said Treasure.

Meanwhile, the use of acoustic panels can dramatically change the user experience, according to Wright. An example is the renovation of the auditorium at Aspen Academy in Denver where Primacoustic was involved. The company’s wall and ceiling panels helped resolve reverberation and sound bleed issues inside the auditorium.

“School administrators were so happy with the results that they have now commissioned an acoustic treatment project for the cafeteria, which also has similar reverberation and intelligibility issues,” Wright said.

Another example is Simon Fraser University in Vancouver. A decade ago, the school decided to remove all padded seating and carpeting from their concrete lecture halls. Soon they realized that students could not learn in those rooms because they became echo chambers.

“By covering 20 percent to 25 percent of the wall surface area with acoustic panels, the lecture halls became very balanced and very desirable again to use as lecture centers,” Wright added.

According to DLR Group’s Lembke, their integrated design practice employs higher STC (sound transmission class) ratings “in our demising walls between classrooms and extend those walls to structure to limit noise transfer.”

They also recommend LED lights to eliminate noisy ballasts; fresh and conditionedair is distributed through ducted and dampened systems; and the air speedis sufficiently slow enough not to impact conversation or quiet study. Furniture with“soft” feet allows for ease of movement without nuisance noise or vibration.

Yet, the cost of improving the acoustical environment remains a challenge for school districts where sometimes the priority is investing money in athleticfields compared to students listening in the classroom.

“We need listening now more than ever because conscious listening is the doorway to understanding,” said Treasure.

This article originally appeared in the School Planning & Management September 2019 issue of Spaces4Learning.