Noise and Healing
Although everyone’s perception of what constitutes “noise” is different, most patients would agree that hospitals are and have always been noisy places. While the World Health Organization recommends that average patient room noise levels remain around 30 decibels, typical noise levels often hover as much as 20-30 decibels above that level.
The incessant beeps of bedside monitors, the squeaky wheels of rolling carts and housekeeping dollies, ice machines, pagers’ beeps, cell phones’ rings and the constant buzz of conversations remain a largely unsolved problem in healthcare environments. Very rarely can patients enjoy a quiet moment, let alone undisturbed sleep through the night.
Designing a Quiet Environment
It all starts with walls. They are the basic physical barriers between patients and noise sources. They block sound movement fairly effectively if they are continuous floor to ceiling, have mass, integrate sound-absorbing materials and are not compromised by various penetrations. On many projects we utilize a special gypsum wallboard between patient rooms to achieve the required STC rating (sound transmission class - a measurement of the sound transmission of a wall) such as Gold Bond - Soundbreak XP or CertainTeed - SilentFX.
Headwalls in patient rooms which are typically designed to be back to back for sharing of utilities should be offset from one another so that electrical boxes and other connection points don’t align and therefore don’t transmit sound from one room to another as readily.
Properly constructed doors also act as noise buffers, although they are often kept open to provide patient visibility for nursing and especially at nighttime, noise is transmitted into the room. In the Medical/Surgical Inpatient Unit at New York Presbyterian Hospital, we placed a full height vision panel in each patient room’s door to eliminate the need for open doors. Partially or totally transparent or translucent panels provide a level of noise control while maintaining an open line of sight.
Space Layout to Reduce Noise
Reducing sound transmission though walls and doors is critical, but careful arrangement of spaces can reduce sound transmission more than any wall. For example, most hospitals in the U.S. still have a majority of 2-bedded rooms, although most hospitals are now working to create more private rooms, which dramatically reduce patient room sound levels, as well as providing other benefits such as reduced hospital acquired infections and reduced transfers.
As important as private patient rooms are to reducing noise, the separation of clinical staff spaces from the patient space may be of equal importance. We are currently designing an ICU for the VA in Northport, New York in which each pair of rooms has a nursing work area in-between that provides visibility through glass that allows nurses to do their paper work, while supervising & observing patients in both rooms at the same time.
Changing shifts are known to provide very high levels of noise. While one set of nursing staff is going off duty, another one is coming on duty and the exchange information about patients often occurs in a nursing station open to the corridor. Although a central location of some sort is always needed, open-nursing designs increase the level of noise while decentralized dispersed smaller working stations reduce the concentration of people and the sound emanating from their activities. As architects, we need to make sure the design provides an enclosed space for nurse report to happen quietly in a space that is acoustically isolated from patients.
Although this is an obvious but often overlooked plan of action, hospitals need to work on reducing noise levels through the replacement or treatment of hard, reflective surfaces with sound absorbing materials. Of all the finishes in the built environment, flooring is the one that has the most significant impact on noise and occupant comfort.
Most healthcare facilities are interested in flooring that is durable, has a long service life and can easily be cleaned & disinfected. So more often than not they use hard surfaces made from natural or synthetic rigid materials such as VCT, one of the most durable materials ever invented.
However, hard surfaces are reflective and reverberate sound rather than absorbing it. Resilient surface flooring, such as rubber, luxury vinyl tile, and sheet vinyl, is far better at insulating sound. Carpet is even more sound absorbing compared to terrazzo and rubber flooring, but in a healthcare setting, carpeting is harder to keep clean than nonporous, hard-surface flooring, and cannot be reliably disinfected, especially after spills of fluids.
Another key material for sound absorption is ceiling tile. The selection of ceiling tiles with a high NRC rating (Noise Reduction Coefficient) is important – most manufacturers now offer the same “visual” tile with different ratings (and different price points) so that we can respond more effectively to the specific acoustical needs in a specific space. Thus, in the patient corridor where much noise is generated might use a higher NRC rated tile vs. the patient room where less noise is generated.
The Evolving World of Healthcare Design
As more data is developed around the relationship between design and healing, those of us in the design community are striving to create designs that will result in healthier patients, happier staff and reduced operational costs. Noise reduction is just one of many areas that we are looking at to make a meaningful improvement in the design of healthcare facilities.