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UC San Diego Researchers Try To Quiet Noisy Hospitals

Professors Eve Edelstein and Peter Otto work on noise reduction technology in a lab at Calit2.
Angela Carone
Professors Eve Edelstein and Peter Otto work on noise reduction technology in a lab at Calit2.
UC San Diego Researchers Try To Quiet Noisy Hospitals
Studies show that noise not only disturbs patients’ sleep, it can also cause spikes in blood pressure.

When San Diegan Merry Maisel’s 92-year-old mother entered the hospital after a fall in 2002, she was put in an intensive care unit overflow unit with six other patients. There were heart monitors beeping, TVs on and loud chatter from the nurses’ station.

Maisel believes that noisy hospital visit started her mother’s downward spiral. "She would jerk at each noise. She would shudder," Maisel said. "She must have felt it as an attack."

Maisel's mother died six weeks later, from complications stemming from the fall.

Noise in hospitals has been a problem for decades.

Studies show that noise not only disturbs patients’ sleep, it can also cause spikes in blood pressure.

Eve Edelstein, an associate professor at the University of Arizona as well as a neuroscientist and architect, has measured the sound levels in hospital emergency rooms during shift changes as new staff enters the building.

"All of the equipment is going for 20 patients. And now 20 more nurses walk in and they’re each having one-to-one conversations about each patient's status and everyone’s speaking above the level of the EKG alarm and the overhead announcements and the ventilator systems," Edelstein explained. Sirens and sounds from nearby ambulance bays also add to ER noise.

Normal speech measures between 45 and 65 decibels. During those shift changes in ERs, Edelstein has measured sound levels as high as 100-110 decibels. "That’s as loud as a jet engine," Edelstein said.

It’s not just a problem for the patients. Hospital staff have told Edelstein that noise pollution contributes to their stress. One nurse said her ears ring after she leaves the hospital.

Edelstein is working to find ways to reduce hospital noise. She's found an ally and collaborator in UC San Diego music and sonic arts professor Peter Otto.

Otto has a lab at the University of California, San Diego's California Institute for Telecommunications and Information Technology, or Calit2.

Otto has developed a device called the sound bender. It’s small, the size of a cable box. It has 12 speakers and can direct sound like a laser beam. In a clinical setting, that laser beam could be directed at a nurses' station.

"We’d like to be able to do announcements that just the nurses can hear and that are not going to wake up patients when they’re dozing," Otto explained.

The sound bender points sound in a distinct direction and doesn’t let it spill over. Otto shows me how it can create three distinct sound zones in roughly 14 feet of space.

We stand on one side of the sound bender and listen to muzak coming from the speakers. I walk four feet to the center of the room and the sound shifts to multiple voices in a public space. Four feet to the opposite side and the sound tapers to one woman's voice. As I listen to the woman talking, I am standing just feet from the clamor I heard moments ago in the center of the room. I can no longer hear it.

The sound bender could be used to efficiently direct sound to only the people who need to hear it. Like in operating rooms, explained Otto, where there are a lot of alarms. "What if we just had the interesting messages for the anesthesiologist pointed at him and the things the surgeon needs to pay attention to are only directed to his or her listening space," Otto said. "The nurses might have another stream they are paying attention to."

Otto is working on more than the sound bender.

Sounds bounce around a hospital. It's a matter of simple acoustics. There are not a lot of absorptive materials on walls, floors, or ceilings. They’re hard to clean, so most hospitals have hard surfaces.

In his lab, Otto can test combinations of building materials to reduce noise and enhance sound clarity.

Sitting in front of his computer, we look at a virtual patient room. A nurse reads medications with names that sound alike, such as aspirin and adrenaline.

Otto changes the room’s building materials to see which allows us to hear the nurse more clearly. First he installs vinyl concrete, which creates an extreme echo. Otto switches to four walls of plate glass. When he adds heavy carpet, the nurse's voice becomes clear and sharp.

He can alter the size and shape of the room, which also changes the acoustics. Experimenting like this is cost effective. Architects don't have to draw up expensive mock ups. More importantly though, mixing these elements allows designers to better predict sound clarity in hospital rooms.

Otto specialized in music composition and cello performance, but he's always been fascinated by the physics of sound. He started thinking about sound in clinical environments when observing his young autistic son at kindergarten. There was a large heating and air conditioning unit, or HVAC, on the roof of the temporary mobile unit where class was held.

"There was vibration and low frequency and high frequency HVAC noise in that room and the kids were just bouncing off the walls," Otto remembered. The way to fix this seemed simple to Otto, but no one seemed to be paying attention. "It could be so much more of a healthy, relaxed, focused environment," Otto said. "I started thinking about it more seriously and professionally."

Maisel, whose mother suffered during her hospital stay, says just paying attention to hospital noise will make a difference for patients.

"There’s noise everywhere," she acknowledged. "Because of that, people treat it as tertiary and say there’s nothing you can do about it," Maisel said.

"But if people did something about noise [in the hospital], I think they’d see better outcomes."