Patients, visitors, and staff often complain about the amount of noise in hospital settings. However, in addition to being annoying and disrupting sleep, some research suggests that high sound levels negatively affect the speed of wound healing and the number of medications, as well as contributing to staff stress and burnout. Most research in this area has focused on overall noise levels rather than spectral quality, tonality, and time variance, which limits the discussion around noise in terms of human physiological and psychological response.
The authors conducted a literature review and noise survey at Johns Hopkins Hospital in Baltimore, Maryland. Their results compare noise standards and trends with case study-based equivalent sound pressure levels as a function of location, frequency, and time of day.
The researchers started with a literature review to determine typical hospital noise levels and trends as well as identify established guidelines and standards. Next, they measured sound pressure level in the hospital at five locations: the pediatric intensive care unit, Children’s Center, adult medical/surgical unit, and two locations in the oncology center over the course of 1 year. They measured equivalent sound pressure levels for 1 minute at various locations on each unit (e.g., patient rooms, hallways, and nurses stations) and obtained octave-band sound pressure levels at the same time. The researchers then collected 24-hour hour measurements at a minimum of three places per unit—a patient room, a nurse station, and an examination room or empty patient room. In every case, the researchers asked patients, staff, and visitors to continue with their normal activity. The investigators used a Larson-Davis System 824 near the center of the room at a height of roughly 4.5 ft and downloaded the measurements to a computer for analysis.
The literature review revealed that the World Health Organization (WHO) was the most frequently cited and included guidelines for hospitals that recommend a maximum sound pressure level of no more than 40 dB(A) (re 20 µPa) at night measured on the fast setting. Further, the researchers noted that WHO suggests that patient rooms have an equivalent sound pressure level of no more than 35 dB(A) during the day and 30 dB(A) at night. The authors also note that the American National Standards Institute Inc. recommends a maximum RC(N) (neutral spectrum room criterion) value ranging from 25 to 40 depending on the room type, and a maximum balanced noise criterion value ranging from 25 to 40. Finally, the authors reported that the Environmental Protection Agency makes its recommendations in terms of the Ldn (day-night sound pressure level), which should not exceed 45 dB(A). The researchers found that none of the locations in the study complied with current WHO guidelines. Further, their review of objective data showed that held true in hospitals worldwide as data gathered at various facilities over the last 45 years indicate a trend of increasing noise levels during daytime and nighttime hours. These high sound pressure levels interfere with sleep, potentially affect speech intelligibility unless voices are raised, and create a general annoying din.
Although the authors speculate that noise problems exist at most modern hospitals based on their literature review and the outcomes of the Johns Hopkins Hospital case study, a case study sample inherently limits generalizability. The study did not investigate or correlate medical errors with noise problems.