A remedy for hospital noise

The Baltimore Sun

Tour a hospital with James West and you begin to notice something - it's a noisy place.

Alarms on patient monitors are always beeping. When supply and cleaning carts clatter by, staff and patients have to raise their voices to be heard. Overhead paging systems and chirping telephones create a cacophony that makes it hard to work - and harder to heal.

The 76-year-old West is trying to change that. The solutions can be as simple as replacing noisy public address systems with silent pagers, or as complex as finding new materials to absorb noise without risking patient safety.

As an acoustics professor at the Johns Hopkins University, he knows something about these issues - in fact, he was co-inventor of the electret microphones that millions of us use every day in our telephones and tape recorders. He joined the Hopkins faculty in 2002 after four decades developing audio technology at Bell Labs New Jersey - a career that this summer brought him the nation's highest honor in his field, the National Medal of Technology.

"He was a terrific catch for Hopkins," said Ilene Busch-Vishniac, who worked with West at Bell Labs in the 1980s and recruited him when she was the school's dean of engineering.

Even so, making hospitals quieter is an uphill battle. Experts say hospitals are designed to provide patients with effective and efficient care. But they also present obstacles to fighting noise.

For example, the ubiquitous sound-absorbing carpets and acoustic ceiling tiles in many workplaces are prohibited in hospitals because they harbor bacteria and are hard to clean.

The result is an environment with tiled floors, paneled walls and bare ceilings that reflect sound the way mirrors reflect light, West says. Together, they create a series of echo chambers.

"All these units have always been noisy, and we know why," said Anita Reedy, nurse manager of an oncology unit at Johns Hopkins Hospital. "We can't have carpets and acoustic ceilings because we have immuno-compromised patients."

When he walked into Reedy's unit in the Weinberg Building last week, West focused immediately on the floor plan: Its four corridors connect at right angles. That means sound travels the hallways without barriers, and conversations at one end of a hall can be heard at the other.

Recessed areas in the ceiling above the nurses' station, where two hallways intersect, also amplify ringing telephones - and any conversations.

"It's really not the best design in terms of sound," West said. So he's looking for a material he can use to develop hygienic and affordable fiberglass soundproofing panels for Hopkins and other hospitals.

Recordings of voices and other everyday sounds on Reedy's unit show that the custom panels that West's team attached to the ceilings in 2005 cut noise levels in half. West plans to present those results to the Acoustical Society of America next month.

Unfortunately, those panels cost about $15,000 to install - too expensive for installation at Hopkins and other hospitals. "To make this work, we have to find something affordable," he said.

West has been solving acoustical problems since his days as an intern at Bell Labs in 1957, when he was majoring in physics at Temple University in Philadelphia.

Over the years, he has studied the way sound travels - whether it's through the confines of electrical wiring or inside the world's great concert halls, including Lincoln Center's Avery Fisher Hall, Carnegie Hall and the Academy of Music in Philadelphia. Workmen closed gaps in ceiling panels in Avery Fisher Hall years ago after West and his colleagues discovered they were causing acoustical problems.

Individually or jointly, West holds more than 40 U.S. and 200 foreign patents. At Bell Labs, he and Gerhard Sessler invented the electret microphone, a tiny device made from thin sheets of polymer that makes voices easier to hear.

The electret is used in over 90 percent of the world's telephones, camcorders and other recording devices, a success that earned West a place in the National Inventors Hall of Fame in Akron, Ohio.

"I think he's one of the top people in the field of acoustics," said Sessler, on the faculty of Darmstadt University of Technology in Germany. The Bell laboratories where they worked are now part of the Paris-based Alcatel-Lucent communications giant.

West's noise reduction efforts at Hopkins began about three years ago, when hospital officials asked him and former engineering dean Busch-Vishniac to examine the pediatric intensive care unit.

"This can be a real noisy place," said Claire Beers, the unit's nurse manager. Each child is connected to monitors that sound alarms if there are problems with vital signs, including blood pressure and heart rate levels, Beers said. Many of the unit's patients also are hooked up to ventilators and up to six different infusion pumps.

"And all of them have alarms," Beers said.

When Reedy heard about efforts to make things quieter in pediatrics, she asked if West could work on her ward as well. "We could hear everything going on around here, even if it was down the hall, as if it was right next to us," Reedy said.

In fact, hospital noise levels have been rising steadily since the 1960s. "There's really been almost no intensive work on making hospitals quieter," West said.

For their project, West and Busch-Vishniac took 24-hour sound measurements in the oncology and pediatric intensive care wards. They found that daytime levels were about 72 decibels, and night levels were was as high as 60.

The average daytime decibel level in 1960 was 57, and today the World Health Organization recommends noise levels no higher than 35 decibels in patient rooms.

Given that the average conversation is conducted at 60 decibels, the noise on hospital wards might not sound like a significant problem. But West says a constant 60-decibel din produces stress on patients and medical staff.

"It means people have to raise their voices to be heard," West said. "It's a safety hazard."

Studies have shown that noisy environments slow healing. When staff and patients have to talk louder than normal to overcome the din, it increases fatigue and the chance that someone will misinterpret what's being said - a serious problem in settings where doctors order medications and medical tests.

Error rates by 200 doctors, nurses and pharmacist trying to recall the names of drugs after hearing them on audio recordings fell 20 percent for every five decibel reduction of background noise in a recent study conducted by Bruce L. Lambert, a professor of pharmacy administration at the University of Illinois, Chicago.

"You don't have to be Einstein to know that auditory errors are more common in noisy environments than in quiet ones," Lambert said.

Heart rates and stress levels also increased among 11 nurses at the Hopkins pediatric intensive care unit when noise levels increased, according to Dr. Wynne Morrison, a pediatric intensive care specialist at the Children's Hospital of Philadelphia. She conducted the research when she was at Hopkins in 2002.

"Hospital noise is just starting to be studied. I think a lot of people are starting to realize it's a problem for patients," Morrison said.

Busch-Visniac said she also was struck by the harsh sound of the overhead pediatric paging system. "It was loud, the tonal quality wasn't very good and it was constantly going off," said Busch-Visniac, who left Hopkins this summer to become provost at McMaster University in Ontario.

The researchers proposed two solutions. For the pediatric unit, they suggested personal staff pagers to cut down on the use of the overhead public address system. The personal pagers cut down on the noise and have either been adopted or are being considered by managers in other areas of the hospital, Beers said.

In the cancer unit, the researchers wrapped fiberglass insulation inside an antibacterial fabric to create sound absorbing panels that weigh about two pounds and are about 2 feet by 4 feet in size.

In another cancer wing, they installed commercially available sound panels to compare the effectiveness of the homemade and the commercial product. In both wards, they used Velcro because drilling holes in the ceilings would have been disruptive.

The result was noticeably quieter hallways, particularly where the custom-made panels were installed. The difference was evident during a brief tour last week.

"There's no question that they helped," Reedy said. "Footsteps sound like footsteps now, and not like horses coming through."

To measure the difference, West made audio recordings that clocked reverberation time, or the amount it takes for sound to decay to where it can no longer be heard. At an indoor swimming pool or a gymnasium, the sound of someone's voice can take one to three seconds to become inaudible. In a carpeted living room, it can take a half-second.

The custom-made panels cut reverberation time from 1.2 seconds to about 0.6 seconds, he said.

The biggest stumbling block to installing the high-tech noise panels is cost, West said. Installing 60 homemade panels cost about $15,000 - for one small ward. The cost of covering a sprawling medical complex would be prohibitive, he said, so he's looking for cheaper materials.

A promising candidate for cheaply encasing fiberglass panels is a variation of a material called Tyvek, manufactured by DuPont, that West tested in the acoustic chamber on Hopkins' Homewood campus.

The company also makes a sterile variety of Tyvek for encasing medical equipment and supplies, said Joseph King, global technology manager for DuPont Building Innovations.

"It's very good in terms of cleanability, it's strong and it's smooth," King said. It also is relatively inexpensive, with the home construction variety running from $135 to $150 for a 9-by-150-foot roll.

The next step for West is to make a set of less expensive Tyvek panels, install them in a Hopkins operating room and see if they cut noise levels there. But work on that project will only begin when West can find funding sources, which could be months or years away.

"What we know now is there's clearly a noise problem in hospitals," West said. "What we're doing is a kind of response to a cry for help."

dennis.obrien@baltsun.com

To hear an audio recording of hospital noise before and after sound-absorbing panels were installed, visit www.baltimoresun.com/noise.

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