Interiors

Quiet, please!

Achieving effective acoustics in the hospital setting

By Niklas Moeller

Noise is a significant problem in many hospitals. A recent study by MacKenzie and Galbrun found that there were no less than 86 different sources, including patients, staff and visitors talking, as well as the cacophony produced by televisions, alarms, carts, doors, medical equipment and mechanical systems.

The impact of noise

While it is true that these sounds can set the emotional tone for the environment, they cause more than irritation. A growing body of research shows that noise actually harms patients by, for example, elevating heart rate and blood pressure, increasing muscle tension and gastric secretion and even suppressing the immune system.

In addition, noise prevents patients from getting the rest they need for recovery. While it is not responsible for all awakenings, its contribution is significant. Sleep deprivation can weaken the immune system and lead to problems during the day such as agitation, delirium and decreased tolerance to pain.

No wonder patient satisfaction surveys indicate that noise is the leading patient complaint by a two-to-one margin.

But patients are not the only ones affected. Though it might appear as though staff can become hardened to noise over time, no one is able to fully tune it out because our senses are designed to detect such changes in our environment. Noise makes it difficult to concentrate, causing stress and fatigue, and potentially affecting not only workplace satisfaction but also quality of care.

Speech privacy is another acoustical concern in health care settings. Patients know that it if they can overhear conversations occurring in neighboring areas, others can hear them as well, making them uncomfortable and less likely to discuss private matters with their caregiver. In the United States, their right to oral privacy has also been officially recognized in the Health Insurance Portability and Accountability Act (HIPAA), which requires health care entities to take "reasonable safeguards" to protect in-person and telephone communications.

Rethinking acoustics

As a result, those who design and work in hospitals are rethinking how they approach acoustics. The most noticeable instance is the release of the 2010 FGI Guidelines for Design and Construction of Health Care Facilities, which, for the first time, includes a significant amount of information and recommendations relating to acoustics.

Hospitals will certainly benefit from applying the prescription acoustic professionals use to address noise and speech privacy: absorb, block and cover. These methods are often collectively referred to as the "ABC Rule." Though there are many different environments within each hospital--including reception areas, patient rooms, nursing stations, NICUs, staff lounges and more--these methods and materials can be used in most areas. While they are most cost-effective when planned from a project's outset, many are easily retrofitted.

Absorptive materials reduce the volume of noises, the length of time they last and the distance over which they travel.

Absorbing noise. Hospitals often feature hard finishes that cause noises to echo, overlap, linger and travel great distances. Adding absorptive materials that still meet the criteria for sterility and washability will reduce the energy of noises reflected off of their surfaces, lessening their impact.

The ceiling can be a significant source of absorption. In fact, a Swedish study determined that cardiac patients in rooms with absorptive ceiling tiles were less likely to be readmitted than those in traditional rooms. Select a tile with a high noise reduction coefficient (NRC) rating and ensure consistent coverage throughout the building.

The absorptive power of the ceiling will be affected by the type of lighting system used in the space. From an acoustical perspective, the best lighting is an indirect system because it helps to maintain the coverage of the acoustical tile across the entire ceiling. Choose a system that incorporates a minimum number of fixtures while still meeting the lighting requirements.

Hanging absorptive wall panels may also be needed in some situations. They are most effective when applied to large vertical surfaces and key reflective locations, such as corridors. Additionally, soft flooring can be used to lessen footfall and other traffic noise.

Blocking noise. Blocking is another method used to control noise. The most basic barrier is a wall, such as those around private patient rooms. However, a well-planned layout can also be used to minimize direct (i.e., line of sight) noise transmission. For example, high activity areas and machines such as icemakers should be located in areas that are well-separated from patient rooms.

Blocking noise is achieved through the use of physical barriers and a well-planned layout.

HVAC components must be properly treated to prevent them from providing paths for noise.

It is also helpful to rethink traditional aspects of the hospital landscape. The Karmanos Cancer Institute in Detroit, for example, not only installed acoustical panels, but also decentralized their nursing stations in order to prevent large groups from talking near patients' rooms. Some hospitals are also re-evaluating their open door policy in an attempt to block noise.

Of course, caution needs to be taken when applying blocking tactics in hospitals, because caregivers need to be able to readily monitor and access patients.

Covering noise. When attempting to solve noise and speech privacy problems, many people pursue strategies in the 'Quest for Silence' — the mistaken belief that effective acoustics will have been achieved when the sound levels in the space are as low as possible, with zero being the best.

However, just as with other ergonomic factors, such as lighting and temperature, there is a comfort zone for the volume of sound. Accordingly, ensuring a sufficient background sound level is the final requirement of the ABC Rule.

A sound masking system covers noise, increases speech privacy and reduces sleep disruptions.

Sound masking systems are used to maintain the background sound level at an appropriate volume. These systems consist of a series of loudspeakers, which are usually installed in a grid-like pattern above the ceiling. They distribute an engineered sound, which most people compare to softly blowing air. This sound effectively covers noise and speech, while remaining comfortable and unobtrusive. In addition, because it is not a physical barrier, it does not impact caregiver access.

Sound masking has also been found to be a very effective method of improving sleep. In fact, in a study of ICU patients, quality of sleep improved by 42.7 percent when sound masking was used. The system's success lies in its ability to decrease the magnitude of change between baseline and peak volumes. It is this change, rather than the volume of the noise itself, that determines whether or not disruptions occur.

Hospitals such as Modesto Memorial in Modesto, Calif., have successfully installed sound masking systems in patient rooms. The range for these rooms has increased to NC/RC(N) 30-40 in the 2010 FGI Guidelines for Design and Construction of Health Care Facilities. Though this level (approximately 35 to 45 dBA) might appear high, it is well below that shown to decrease sound perception through a stethoscope. Furthermore, because masking requires some distance to become effective, when set to an appropriate volume it will not prevent patients or staff from understanding one another.

It is important to look for a sound masking system that can provide local control for individual rooms or areas, allowing occupants or staff to adjust the volume as needs require.

Reducing noise at the source. One tactic overlooked by the ABC Rule is reducing noise at the source, which involves the identification and subsequent reduction or elimination of unnecessary sources of noise.

Suggestions include purchasing quiet hand towel dispensers and door hardware, as well as rubber-wheeled carts; fixing or replacing faulty equipment, such as squeaky carts; limiting or eliminating the use of overhead paging; lowering the ringer volume on telephones; turning off unwatched television sets and/or requesting that patients use headphones; responding to alarms promptly; and providing training on how to handle loud vocalization by patients.

It is also important to raise caregivers' awareness of their own actions, such as talking loudly or yelling down the hallway at each other. Some hospitals have asked staff members to form a special committee to develop and enforce policies aimed at controlling noise. Visitors should also be educated about the negative effects of noise and encouraged to follow the rules.

Applying solutions

People will always create noise as they converse and perform tasks. After best efforts have been made to reduce noise at its source, all the noises that remain are there by necessity or because they are impossible to eliminate. These noises, and speech privacy concerns, must be addressed through absorption, blocking and covering up. These design strategies are very effective and do not add to the burden of caregivers, who are already stretched thin. The challenge for those involved in the health care field is to apply them in such a way so as not to compromise staff's ability to provide quality care.

Niklas Moeller is vice-president of K.R. Moeller Associates Ltd., a Burlington, Ontario, developer and manufacturer of sound masking system, LogiSon Acoustic. He can be reached at nmoeller@logison.com.