The Inhospitable Hospital: No Peace, No Quiet

The Inhospitable Hospital: No Peace, No Quiet

Have you ever dropped a heavy book in a library? Or sneezed in church? Or had your cell phone ring during a concert? You know what happens -- everyone turns around to see where the sound came from, and the culprit is duly ashamed of making noise in a "quiet zone."

We never talk loudly in libraries, churches, or funeral homes out of respect for their traditions of quiet. We even whisper in museums. Isn't it odd that in the one place where we can actually disturb someone, we don't worry as much about making noise? The same culture of quiet just doesn't exist in a hospital the way it does in a theater during a play.
How Noisy Is Healthcare?

Healthcare just keeps getting noisier. The average daytime sound level in acute care hospitals grew from 57 decibels (dB) in 1960 to 72 dB in 2005.[1] Nighttime noise is just as severe as daytime noise, and weekends are no quieter than weekdays.[2] In 1960, nighttime noise averaged 42 dB(A) compared with 60 dB(A) today.[1] Peak noise levels in hospitals can be as high as 85-90 dB(A) -- comparable to being 3 feet away from a food blender or standing near traffic when a motorcycle rumbles by. (Most discussions of noise use an A-weighted sound scale, expressing sound in dB(A) -- see description later in this article.) The World Health Organization (WHO) recommends that background noise in a patient's hospital room should be no greater than 35 dB(A) during the day, 30 dB(A) at night, with peaks no higher than 40 dB(A).[3] Noise levels in excess of these guidelines are believed to disturb sleep, contribute to stress, and interfere with communication.[4]

Engineers and acoustic experts Ilene Busch-Vishniac and James West have a lot of experience measuring sound in hospitals. A few years ago, they characterized the sound environments of a broad range of patient care areas at Johns Hopkins Hospital, from pediatric intensive care, medical-surgical units, and emergency department to operating rooms and oncology floor.[1] Using a precision sound level meter, Busch-Vishniac and West recorded sound levels as a function of location, time of day, and frequency, in both new and old hospital buildings, and compared findings to published hospital noise studies from around the world. "We came to the conclusion that regardless of country, regardless of type or size of hospital, and regardless of type of patient care unit or time of day, there is a fairly narrow range of sound levels in hospitals, and all exceed recommended levels."

Busch-Vishniac explains that the problem in hospitals is all of the hard surfaces and right angles that reverberate, or reflect sound, and few surfaces that absorb it. Soft or sound-absorbent surfaces aren't hospital friendly because they can harbor micro-organisms and are difficult to clean.

Table 1 represents average sound levels, measured in various patient care environments of different hospitals. For comparison, Table 2 provides typical sounds and corresponding dB levels.

Understanding Noise and Sound Level Measurements

Noise is measured as a sound level, in dB. One dB is one tenth of a bel (named for Alexander Graham Bell). A dB is not a unit of measurement; rather, it is a number that represents how much a sound differs from a reference point.

The threshold of hearing is 0 dB(A), and the sound of a rocket launching is 180 dB(A). The human ear can tolerate sound up to about 120 dB(A); sounds above 85 dB are associated with hearing loss. Most discussions of noise in hospital settings use an A-weighted sound scale, expressing sound in dB(A). A-weighting is a method of standardizing sound measurement that takes into consideration the sensitivity of the human ear to certain frequencies. An A-weighted sound level meter contains a filter whose response to frequency is similar to the human ear.

The dB scale is logarithmic rather than linear. To make matters even more confusing, sound intensity and loudness, although related, are not exactly the same. Sound intensity is an objective measure. Loudness is what is perceived by the human ear. Sound intensity that increases by 3 dB is perceived as twice as loud, and an increase of 10 dB(A) is 10 times as loud.[12] So a sound of 30 dB(A), which corresponds to a whisper at a distance of 3 feet, is perceived as 10 times as loud as the 20 dB(A) sound of rustling leaves. Add another 10 dB(A) to reach 40 dB(A), and the sound is perceived as 100 times as loud (Table 2).

Investigators studying sound levels in clinical areas like those in healthcare institutions usually find that sound level is continually fluctuating. Sound levels in these areas are often reported as Leq, which stands for equivalent sound level. Leq represents the sound level of an imaginary continuous signal, within a given time interval, that would produce the same energy as the fluctuating sound.

Sounds greater than 80-85 dB(A) are dangerous, particularly when sustained or repetitive. A sound at 85 dB(A) is 100,000 times higher in sound pressure than the recommended daytime level of 35 dB(A) for patient areas.[12] Both the amount of noise and the duration of exposure are factors in hearing loss. Sensitive hair cells of inner ear and the auditory nerve can be damaged by an intense brief impulse, like an explosion, or by continuous exposure to unsafe noise levels. Hair cells, once damaged, do not grow back.[13]

Noise: Unwanted Sound

The neonatal intensive care unit (NICU), full of sleeping babies, should be a quiet environment. In reality, the NICU is far from quiet.[2,11] Infusion pumps, monitors, and ventilators used to treat sick babies are plentiful, and all have alarms that sound frequently. Telephones ring, doors open and close, packages are torn open. And babies cry, sometimes very loudly.

One day a mother said to me in the NICU that the sound of her baby's cry was "music to her ears." What she meant was that her baby's cry was a normal, welcome sound that made her realize that her baby was going to be okay. Most loud sounds in a hospital, however, are not welcome. Thinking of noise as unwanted sound makes it easier to see that any sound can be interpreted as noise and be a source of annoyance to patients who are trying to rest and recover. Staff members conversing in the hallway, supply carts rolling by, a scale being dragged down the hall -- all are just typical workday sounds to us but perceived as noise by patients.

A good example of this occurs in the emergency department (ED). Most caregivers who work in the ED thrive on the intensity and fast-paced work of caring for trauma patients. The ED may well be the noisiest place in the hospital, 24 hours a day, yet staff working there may not be aware of the noise level.[14] It is no wonder that patients being held in the ED awaiting an inpatient bed would prefer boarding on the ward to boarding in the ED.[15]

Some sounds are pervasive in hospitals, adding significantly to the overall sound level, although we might not notice their sources. Examples are hospital ventilation, cooling and heating systems, refrigerators, vending and ice machines, automatic doors, water running, paper towel dispensers, pneumatic tube systems, printers, and carts rattling down the hallway. Outside, helicopters land on the roof several times a day, and the sound of sirens can be heard approaching the emergency entrance. Even with the use of personal pagers, the overhead paging system is necessary to alert the staff of code situations and other events requiring urgent attention. The typical hospital is people-dense, and people generate a tremendous amount of speech noise. The most frequent sources of noise in one intensive care unit -- rubbish bins, chair scraping, and talking -- are all caused by human activities.[4]

Hospital noises can affect staff and patients differently. A patient may be more bothered by the sound of inappropriate laughter than the sound of the ice machine.[16] Staff, on the other hand, might be more annoyed by alarm sounds. Frequent alarm sounds contribute to overall noise levels in patient rooms and intensive care units. The high number of false alarms can render clinical staff impervious to the sound of alarms.[17]

How Noise Affects Patients

Noise is antithetical to a therapeutic environment. More than a nuisance, noise is a real health hazard.[3] Although the burden of morbidity attributable to noise isn't known, there are indictors that the effects of noise on physical and mental health are significant. One of the most serious implications for patients in a continuously noisy environment is an increased risk of hypertension and ischemic heart disease.[3] Noise-induced secretion of cortisol[18] may be a mediator of cardiovascular responses to noise. Noise studies have also documented delayed wound healing, aggressive behavior, psychiatric symptoms, and increased rehospitalization rates.[3] Moore and colleagues[19] found that surgical patients identified noise as the biggest irritant during hospitalization, and, postoperatively, surgical patients in a noisy environment require more pain medication than those in a quiet setting. Noise can even increase symptoms of heartburn in patients with gastroesophageal reflux disorder.[20]

Noise also interrupts sleep in hospitalized patients, some of whom are particularly vulnerable to sleep disruption. Patients at high risk of having their sleep disturbed by noise include children, very low birth weight infants, pregnant women, anxious individuals, the elderly, and residents of long-term care facilities. The WHO recommends that for good sleep, background sound levels should not exceed 30 dB(A), with individual sounds no greater than 45 dB(A). Intermittent noise might be more disruptive to patients' sleep than continuous noise.
Noise in the NICU

A unique problem exists in neonatal intensive care because preterm infants are exposed to a developmentally inappropriate acoustic environment. Sounds in the NICU are louder, more high-pitched, and more random and unpredictable than those in the womb.[2] Preterm and ill neonates exhibit many unfavorable responses to noise, including unstable heart rate, respiratory rate, and oxygen levels. To promote sleep, the combination of continuous background sound and operational sound in infant rooms should not exceed an hourly Leq of 45 dB(A), the hourly L10 no greater than 50 dB(A) (level that comprises no more than 10% of the time), and transient maximum noise levels in the NICU should not exceed 65 dB(A).[21] To promote effective communication and minimize stress, noise levels in staff work areas, lounge areas, and family areas should not exceed an hourly Leq of 50 dB(A) and an hourly L10 of 55 dB(A), with peaks no greater than 70 dB(A).[21]
Noise in Long-term Care

The gradual, almost insidious hearing loss that accompanies aging is so common, it has its own word: presbycusis. Presbycusis affects both ears equally and is greater for high-pitched sounds.[22] The individual with presbycusis might be able to hear the low, rumbling sound of a truck, but not the ringing of the telephone.[21]

The pattern of noise in a nursing home, like that in the hospital, follows human factor activities.[14] Sound levels of 55-70 dB(A) were measured in one nursing home, levels that were lower than those in a teaching hospital. Residents transferred from long-term care to acute care might experience increased stress from additional noise.[14]

Long-term care facilities could do more to promote independence of their residents by creating living environments that enhance, rather than aggravate, the diminished hearing acuity of the elderly.[23] Susan Mazer, President and CEO of Healing HealthCare Systems, blames poorly designed physical spaces and routines often found in long-term care facilities. Noise reverberates in large dining rooms with high ceilings and hardwood floors. Radio and television played on overhead paging systems contribute to high background noise that makes locating ambient sounds difficult for residents. Intercoms are often unintelligible, and distracting noise such as vacuum cleaners, dishwashers, and fans are simply noxious. Music, used inappropriately, becomes a nuisance rather than an asset.[23]

How Noise Affects Staff

Noise is an environmental stressor. No one likes noise intruding into their personal or work space. The problem is, noise is pervasive in the hospital, so we become accustomed to it and miss opportunities to reduce it. We may not even be aware of the impact of noise on our ability to concentrate on tasks, or if we are, we tend to try to work around excessive noise rather than eliminating it. When our work environment becomes noisy, we compensate by moving away, raising our voices, or repeating ourselves; in essence, by exerting more effort and working harder.[24]

Sound is considered part of the "psychosocial work environment" in healthcare facilities.[25] Excessive noise can increase perceived work pressure, stress, and annoyance. Noise contributes to fatigue, emotional exhaustion, and burnout. Tachycardia and other physiological responses to noise stimuli have also been demonstrated.[26]

Noise is a constant threat to patient safety by making patient-staff and staff-staff communication more difficult.[24] Although the Joint Commission doesn't specify maximum sound levels for different patient care environments, they mandate that the ambient sound environment should not exceed a level that would prohibit clinicians from clearly understanding each other.[27] Speech intelligibility is compromised most in environments with excessive reverberation.

Is Noise Avoidable?

It's one thing to measure and document high sound levels, but another thing altogether to make lasting changes to reduce noise. Looking at specific sources of noise measured in 2 different hospital intensive care units, MacKenzie and Galbrun[4] believe that 34% of the sources of noise were avoidable, and another 28% partially avoidable. Classifying objectively measured noise as all or partially avoidable can aid priority setting in noise reduction efforts.

Many healthcare facilities have attempted to reduce noise in patient care areas by posting "Quiet, Please" signs, educating staff about noise, and other behavioral interventions. The problem with this approach, according to Busch-Vishniac, is that trying to make permanent changes by influencing human behavior just won't work in the long term. Philbin and Gray[2] found that staff behavioral changes alone weren't sufficient to control noise; their research demonstrated that physical changes to the environment achieved a greater reduction in noise.
Solutions -- What Works? What Doesn't?

Controlling noise is an important intervention in creating a healing environment.[25] Excessive noise, and its effect on rest, are high on the list of complaints made by patients on postdischarge patient satisfaction surveys.[19]

Simply educating staff about noise and noise-reduction measures such as lowering voices and keeping personal pagers on vibrate may not be effective in reducing noise levels.[19] Nurse reports and physician rounds have been moved away from the patient's bedside in an effort to reduce noise.[19] Closing doors to patient rooms reduces noise on general floors but not in intensive care because the sounds from equipment and alarms increase with the door shut.[19] Offering earplugs to patients to reduce irritation from noise has been suggested, although patients should be warned that earplugs won't completely eliminate noise.[28] Others have used foreground music to mask environmental noise.

Busch-Vishniac emphasizes that the most effective way to provide quiet environments for patients, including sick neonates, is with private rooms, and, indeed, private rooms have a beneficial effect on sound.[29] The most effective physical change for noise reduction is to add sound-absorbing material to the environment. Sound-absorbent panels that are resistant to micro-organisms are available for ceilings and walls. Busch-Vishniac and West successfully reduced sound levels on an oncology unit by attaching acoustic fiberglass panels wrapped in antibacterial fabric to the walls and ceilings. This change dropped noise levels immediately by 5 dB and reduced reverberation time by a factor of more than 2.[30]

Based on findings from hospital noise studies, in which they identified 86 different sources of noise, MacKenzie and Galbrun[4] offer these practical solutions for reducing noise in hospital environments:

* Replace metal, lidded trash cans with cans that have a damping system to close the lid slowly or with plastic bins.

* Evaluate use of monitors and alarms to ensure that false alarms are minimized and monitor use is customized to patient need. Set trigger points appropriately.

* Use resilient materials on chair legs to reduce noise from chairs scraping on hard floors.

* Lower telephone volume.

* Change to ring binders with a lever and spring for quieter opening/closing

* Use plastic rather than noisy metal carts.

* Cupboard doors and drawers should also have damping systems for gradual closure.

* Educate housekeeping staff about noise sources and noise reduction related to cleaning activities.

* Use "Quiet, Please" posters to remind staff to reduce noise; turning overhead lights down has been shown to induce people to lower their voices.

When innovations are being considered for the patient care environment, they should first be evaluated for sound production. For example, motion-sensing paper towel dispensers, although convenient and beneficial for infection control purposes, are extremely noisy, particularly when located near patients.[31] In addition to considering the sound impact of new purchases, it might be possible to make adjustments to existing equipment to reduce the noise level.[32]

Recently, some novel approaches to reducing sound levels in neonatal intensive care have been introduced. One company offers a monitoring system that leads to a "Quiet, Please" light that turns on when noise levels are exceeded. Another vendor offers a warning system of colored lights based on traffic lights -- green, yellow and red -- providing a visual cue. Green indicates an acceptable sound level, yellow warns that sound is approaching dangerous levels, and red calls for immediate quiet.

There is no "one-size-fits-all" plan for noise reduction. Facilities aiming to solve their noise problems must first examine the sound environment by conducting a sound and noise study. Susan Mazer provides a step-by-step method, including a data collection tool, to assess the sound environment in an individual department or facility.[16] Mazer suggests using both quantitative (dB levels) and qualitative (patient satisfaction surveys) to develop a complete picture of the sound environment and provide direction for sound-reduction efforts.[33]

Authors and Disclosures

As an organization accredited by the ACCME, Medscape, LLC requires everyone who is in a position to control the content of an education activity to disclose all relevant financial relationships with any commercial interest. The ACCME defines "relevant financial relationships" as financial relationships in any amount, occurring within the past 12 months, including financial relationships of a spouse or life partner, that could create a conflict of interest.

Medscape, LLC encourages Authors to identify investigational products or off-label uses of products regulated by the US Food and Drug Administration, at first mention and where appropriate in the content.

Author

Laura A. Stokowski, RN, MS
Staff Nurse, Inova Fairfax Hospital for Children, Falls Church, Virginia; Editor, Medscape Ask the Experts Advanced Practice Nurses

Disclosure: Laura A. Stokowski, RN, MS, has disclosed that she has served as a consultant for Draeger Medical.