Looks aren’t everything. It isn’t just the appearance of a building that matters, but what it sounds like as well. And every detail needs to be considered when designing the acoustics of a building. The structure, the floor, ceiling and wall treatments, and the building’s planned end use all play a major part in creating comfortable sound levels, which are crucial to making the building functional and its inhabitants productive and healthy.
“In regards to building construction, assemblies really do matter,” explains Celeste Thiesen, contract specialist for Shaw Contract Group. “The amount of hard surfaces incorporated on the exterior and interior need to be evaluated based on whether sound needs to be absorbed or transmitted.”
For example, a school where quiet and concentration are important should be built differently than a restaurant where the emphasis is on customers not overhearing neighbouring tables or providing sound levels that allow for quicker turnover. Building materials (wood versus concrete) and the location (inner city versus suburbs) have an impact on how the structure will sound as well.
Floor to ceiling
On restored buildings, the interior treatments can make a huge difference to quality of sound. Often, when a new company is moving into an office building, it will gut the inside and start from scratch. The contractor will put in a ceiling to cover the entire space then build the walls. This is cost effective and works just fine for a regular office building, but not so well for a law or medical practice.
“The ceiling tile absorbs the sound into the plenum, and then 100 per cent of that sound bounces off the plenum into the ceiling tile on the other side of the wall,” says Darlene Helfrich, architectural sales manager for CertainTeed Ceilings. For spaces needing privacy, the solution is to build the wall right to the underside of the deck—basically, build the ceiling inside the room.
Floors can be another source of acoustical problems. In condo buildings, an owner might prefer to upgrade from carpet to hardwood, creating the need for a much different underlay. In a commercial setting, “a floor is determined by cleanability, so obviously acoustics are going to be better in a carpeted area, but if you’re in an operating room, you’re certainly not going to carpet it,” Helfrich says.
It’s always going to pay to hire an expert to look at (or listen to) the space. What works on one building is not necessarily going to be the right solution for the building next door.
Andre Rioux, vice-president of sales and development for AcoustiTECH, explains using a metaphor. “What is the best Ford vehicle you can buy? A student downtown going to SAIT might say a Focus, but if you’re pulling a boat to go to the lake, you might need an F150,” he says. “One is not necessarily better than the other; it depends what you’re doing with it.”
Sounds like stress
Getting a building’s acoustics wrong can have a serious impact on the people inside. As the Canada Safety Council notes, even low-level unwanted sounds can increase stress levels and impair communication and concentration.
This is no truer than in a hospital. Finding a way to dull the beeping of machines and various other noises benefits not just the patients but the hospital staff as well. Good acoustic design can “improve patient comfort, privacy and dignity; assist in providing essential sleep patterns to aid the healing process; and improve staff comfort, privacy, efficiency and accuracy,” according to a 2011 study by Samuel Clarke of Australia.
“People underestimate the effects of acoustics,” Helfrich says. “They’re more interested in the functionality of having the oxygen and access to the bathrooms. It’s been proven that people who get a good night’s sleep in the hospital heal five times faster.”
Lesson in listening
Acoustics have an impact on every building, but some situations are more serious if ignored.
Schools have been sadly overlooked until recently. Julian Treasure, author, speaker, founder and chairman of the U.K.-based Sound Agency, gives TED talks on acoustics and sound. In one session titled “Why Architects Need to Use Their Ears,” he refers to a study done in a regular Florida classroom. Children sitting in the fourth row were hearing only 50 per cent of what the teacher was saying.
“Children are losing one word in two. Now that doesn’t mean they only get half their education, but it does mean they have to work very hard to join the dots and understand what’s going on,” Treasure says. This does not even take into account children who are hearing-impaired or speak English as a second language.
And it’s not just the students that suffer. Treasure speaks of another study in Germany where the teacher’s heart rate was tested. The average noise level in the classroom was 65 decibels, and every time the teacher’s voice rose so did her heart rate. “In fact, 65 decibels is the very level at which this big survey of all the evidence on noise and health found is the threshold for the danger of myocardial infarction,” he says.
Not only is it nicer to not have to speak over sound or listen to your neighbour’s loud noises, but it’s better for your health as well. That’s why architects, condo boards and contractors should continue to give thought to acoustics for the comfort of their clients. As Rioux points out, “Every single detail in what you’re trying to do will make an impact. Every single one of them.”
Common acoustical oversights:
- Picking a product for aesthetics and not for performance.
- Going for low cost over good sound. Proper acoustics will cost a bit more.
- Not researching the requirements of the space.
- Not giving thought to the HVAC system.
- Assuming that lab results will be replicated at the same level on site.