If it's not the incessant beeping and pinging of medical equipment, it's the rattle of gurneys or busy staff congregating outside patient rooms to exchange information.

"All you need to do is spend enough time in a hospital and you'll realize you don't come to a hospital to get rest," said Dr. Mark Mogul, interim director of the Presbyterian Cancer Center in Charlotte.

The World Health Organization recommends that the noise level in a hospital not exceed 40 decibels, the sound of a quiet library. But a 2005 study found that most hospitals can be twice as loud as that. That's like standing on the side of a busy road and listening to traffic.

Studies show that noise has climbed steadily since the 1960s. The main culprit? The ever-growing herd of medical devices that emit all variety of noises and alarms.

Other studies say that when noise interrupts sleep and rest, it can have serious consequences. Wounds heal more slowly. Hospital stays drag on longer. Surgical patients need more medication.

Hospitals dial down

But hospitals in North Carolina are giving more attention to quieting the din.

A year and a half ago, UNC Hospitals in Chapel Hill started using "quiet" measures: dimming the lights, closing doors and encouraging naps during certain hours of the afternoon.

The hospital also bought a handful of "Yacker Trackers," devices that resemble small stoplights and flash red if noise levels spike. They're usually kept near the nurses' desks - the loudest areas in the hospital, said Priscilla Merryman, the director for Medicine Service at UNC.

It also installed sound-absorbing panels in ceilings and replaced the large wall TVs in shared rooms with smaller, personal sets that come with headphones.

Like many hospitals, it has cut back on using its public address system. Rather than the nurses' desk calling over the loudspeaker, they reach nurses on special phones.

Duke Raleigh Hospital tells patients to dial "L-O-U-D" if they're disturbed by noise, and a nurse's phone will light up. And simple signs that show nurses saying "Shhh" have been effective, said Sharon Brodie, the director of service excellence.

At Presbyterian Hospital in Charlotte, a new wing features thicker walls and floors and more insulation to soak up noise, hospital officials said.

Other changes make a difference, too. Smaller nurse workstations next to patient rooms reduce general commotion that builds when staffers cluster at central nurse desks.

Carolinas Medical Center has adopted many of the new strategies that hospitals across the country are using to control noise, said Dr. James Hunter, chief medical officer. That includes limiting public address system paging, posting "quiet" signs during certain times and using the new nurse workstations. Despite improvements in architecture, technology and staff behavior, hospital noise is inevitable. On a late night in June, the noise of tending the sick created a hushed avant-garde jazz soundscape in Presbyterian's oncology unit:

A patient's call to the front desk chimed out.

Keypads sounded when nurses pushed buttons to enter certain rooms.

A patient's TV droned down the hall.

Elevators arrived with a ding. The wheels of an industrial vacuum rumbled as uniformed workers searched for the source of a leak after a thunderstorm. One of the louder moments: a nurse wheeling a beeping I.V. cart noisily down the hall.

And it took staff a while to figure out the source of one disruption.

"I have no idea what that is," nursing secretary Pat Myers said when a distant but persistent beep began to compete with the other noises. A few minutes later, a nurse emerged from a private room with the answer: Low battery power on a patient-controlled pain device had the machine "going crazy."

Older vs. newer systems

Other noises come with age. In an older wing of Presbyterian, there was a quiet crackle, resembling a wood fire, coming from the speakers on the ceiling, and an ocean-like whir from the air-handling system.

The new F-Wing, which opened in April, has a quieter ventilation system. "They're supplying air to the entire building," said Doug Armstrong, facilities director, "but you can't even hear them."

New patients noticed the difference between the old and new construction.

"This is like the Hilton," said Lynn Starnes, who has spent more than two months sleeping in the hospital as a caregiver for her 77-year-old mother, Delores Maynor. Maynor was the first patient to be transferred to the new wing.

"It was definitely noisier down there," said Starnes, referring to the former oncology unit. "I could hear a lot more movement, and I would wonder what was going on outside."

Other patients in the new wing agreed. In the old wing, they said they heard TVs blaring and nurses talking in the hallway.

But throughout the hospital, staff agree, they're thinking differently about noise.

"They don't roll equipment through the hallways at all hours of the night like they used to," said Vanessa Thompson, a nursing secretary who has worked at Presbyterian for four decades. "They turn off the phones at 10 p.m. because the patient needs rest. A long time ago, we weren't as conscious as we are now."