Noise is unwanted sound. Over the past 50 years, sound levels in hospitals have increased,1-3 with all studies exceeding the recommendations from World Health Organization (WHO) Guidelines for Community Noise.4 In 2006 the Hospital Consumer Assessment of Healthcare Providers and Systems began surveying patients regarding their perspectives on hospital care. This survey specifically asks about noise: “During this hospital stay, how often was the area around your room quiet at night?” In 2013, the responses to this question were included in the calculation of a Value Based Purchasing score, which is linked to payments from the Centers for Medicare & Medicaid Services. To effectively carry out noise reducing interventions it is important to understand what we know about noise in the hospital. This article, which focuses on noise in the Intensive Care Unit (ICU), describes basic sound level measurement terminology, the effect of noise on critically ill patients and evidence-based strategies to which nurses can actively contribute to decrease or protect patients from noise.
Noise in the ICU
Despite the increased emphasis on the need for noise reduction, studies published in the past five years found that sound levels in the ICU continue to exceed the WHO noise recommendations.3, 5-10 To interpret research on noise in the hospital, it is important to have an understanding of the terminology used (Table 1.) Noise is simply unwanted sound. What is noise to one individual may not be to another. Sound levels are reported in decibels (dB), with 0 dB being the threshold for human hearing. A 3 dB change in sound level is just discernible, a 5 dB change is discernible and a 10 dB change is perceived as a doubling or halving of the sound level. In hospital studies, A-weighted sound levels, which reflect the normal range of human hearing, are used. The A-weighted average (LAeq) and maximum (LAmax) sound levels over a period of time are reported. Peak sound levels, which reflect minute by minute sound peaks, are used to describe intermittent, high frequency noise (i.e., the sound of a door slamming) that may not be detected when sound measurements are averaged over time (Figure 1).
An appreciation of how quiet the ICU should be aids in the interpretation of noise research. The WHO guidelines4 state that the average sound level (LAeq) should not exceed 30 dBA in general hospital areas, 35 dBA in rooms where patients are treated or observed and the maximum sound level (LAmax) indoors should not exceed 40 dBA during the night. The Environmental Protection Agency (EPA) recommends that hospital noise levels not exceed an average of 45 dB during the day and 35 dB during night hours.11 To achieve these goals, we need to be as quiet as a whisper, 24-hours a day. A challenge in meeting these recommendations is that ambient sound levels often exceed these levels, and noise from equipment, alarms and conversations in the ICU further increase sound levels. In some cases,...