Vibration, Other Noises Cause Health Care Acoustical Problems
3. Ensuring Intelligibility
Intelligibility is another concern, Ramirez says. Operating and procedure rooms are prime examples, as they often house equipment that generates noise. In addition, most of the surfaces are hard and reflective, contributing to the build-up of noise. The result is that it's often difficult for the medical staff to hear each other.
At the same time, acoustics usually is not the top priority; infection control is, Harrison says. Next in line is temperature and humidity control, and then lighting. Acoustics is fourth. As a result, he says, "there are limited options for adding absorptive materials in operating rooms." Instead, the facility designers can try to construct walls to provide cavity absorption, and design HVAC systems to be as quiet as possible.
Some sound absorbing surfaces, such as rubberized flooring or ceiling materials that feature higher noise reduction coefficients, or NRCs, may be suitable in operating rooms, Ramirez says. The NRC indicates how much sound the material is absorbing.
Vibrations from fans, chillers and other equipment also can present challenges. "If vibration gets into a structure, it becomes noise," Shen says. Vibrations also can hamper the functioning of some equipment, such as MRI machines. One way to solve that problem is to locate sensitive medical instruments away from the source of vibrations. Mounting equipment on vibration isolators can reduce the transmission of vibrations by 90 to 95 percent, Shen says.
The need for isolators will vary with location of equipment and power of the motors, Davenny says. If equipment is on a slab on grade or rigid foundation, it will need less isolation than if it's on the roof. "No raised floor or roof is as rigid as a slab on grade," he says. The more powerful the equipment, the more isolation required.
Activity noise is another concern. Construction materials offer one way to mitigate it. For instance, adding gypsum board to the wall construction can make it more difficult for sound to travel.
In hallways, nurses' stations and patient areas, surfaces, such as wall and floor finishes, that are more sound absorptive than reflective can reduce sound transmission, Shen says. But they also need to be easily cleanable.
An often-overlooked surface is the ceiling, which is almost never touched. "If we can make it highly absorptive, it helps to negate the need for absorptive materials on the floor and walls," Shen says. That can mean using material with an NRC in the range of .8 to .95.
Many health care facilities also are looking at new ways to reduce noise levels at nurse stations, Ramirez says. For instance, some are partially enclosing the stations. That way, any alarms can be quieter, since they'll have fewer other sounds to overcome. In addition, the doors on patient rooms located near a nurse's station may be outfitted with viewing windows, Ramirez says. The room doors can remain closed, while the windows allow the medical staff to monitor the patients.
Reducing noise in most health care environments requires carefully balancing competing design priorities. "It's a challenge for the entire design team to meet all the design criteria for a project, including storage, ventilation and lighting, and then still have a quiet facility that provides a restful environment," Harrison says. At the same time, a growing body of research is showing how reducing noise and sounds in a health care environment can enhance patients' recovery and health.
Karen Kroll, a contributing editor for Building Operating Management, is a freelance writer who has written extensively about real estate and facility issues.
Experience Shows That Improving Acoustics Can Be a Complicated Matter
>> It seemed like a good idea. To cut down on noise coming into patient rooms, Froedtert Health St. Joseph's hospital in West Bend, Wis., designed doors on those rooms to be closed all the time. The strategy was part of St. Joseph's overall focus on safety and patient comfort.
But the closed doors didn't make patients happier, says John Balzer, vice president, facility planning and development, Froedtert Health. St. John's was built before it was acquired by Froedtert Health. While the design did cut down on noise in the patient rooms, patients didn't like feeling closed off from the rest of the hospital.
"The feedback we got from our patients was very negative," Balzer says. "Bottom line is, they wanted to feel connected to the caregiver. They felt too isolated, particularly the elderly patients.
"We would have patients almost get scared; they would feel that they were abandoned because it was so doggone quiet and so isolated in the patient room. Sometimes a little bit of activity and connection — just seeing the doctors and nurses going up and down the hallway — can be reassuring to patients."
>> Froedtert Health has a strong focus on having good acoustics in all its facilities, Balzer says. Strategies such as carpet in hallways, sound-absorbing ceiling panels and buying equipment with low noise ratings helps with that goal. But facilities are only one side of the story.
"People tend to really focus on the facility component, and that's certainly an important piece of it with flooring materials and walls and ceiling materials, but we found that you've really got to keep a well-rounded, blended approach to it," Balzer says. "Probably the most important piece of it is the staff piece." Balzer says that the medical staff has embraced the idea that by being mindful of the noise level, they can help improve patient comfort.
>> For facility managers looking to improve their acoustics, Balzer has one more piece of advice: Pay attention to the little things, like the small rubber door silencers that are almost universal on patient room door frames.
"It's amazing how that is forgotten," he says. "In a matter of two or three years, those things are worn away to nothing. And when they're worn away, the door makes a god-awful racket when you close it."
— Casey Laughman, managing editor