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above, stationary sound level meters were used at the patient
location while staff members wore body-mounted dosime-
ters. The average staff exposure levels were found to be
between 12 and 13 dB(A) Leq higher than the levels at the
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patients. For example, while it is critical to understand
speech within individual treatment spaces, adequate sound isolation must ensure that one cannot hear the diagnosis of the patient in the next room. Therefore, a holistic approach must be taken in the acoustical design of any ward.
Our primary goal is to understand better and to improve the hospital soundscape. Although much progress is being made, there is much more to learn. We will continue to inves- tigate a variety of facets of this unique acoustic environment. This includes research on improvement of acoustic measure- ment and characterization techniques, response of occupants to the soundscape including psychological and physiological reactions as well as medical outcomes and errors, and identi- fication and evaluation of acoustic treatments and noise mit- igation strategies. Ultimately, we hope that our research facil- itates change in the hospital soundscape—creating a safer, healthier environment for patients, staff, and visitors.
Acknowledgments
This work has been supported by the Acoustical Society of America, the Swedish Council for Working Life and Social Research, Fulbright, and Johns Hopkins Hospital. We greatly appreciate the participation of the patients, staff, and admin- istrators at Johns Hopkins Hospital, Emory University Hospital, Sahlgrenska University Hospital, and Parkland Hospital for their participation and assistance. We are indebt- ed to our research collaborators, including: Berit Lindahl,
It was hypothesized that these differences were primarily due to staff speech noise and activities close to the wearer. A separate study was then con- ducted to further investigate the effects of wearer’s voice on body-mounted dosimeter measurements in sixteen noise
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Research to date has focused primarily on characteriza- tion of the sound environment. What remains to be done is to better link physiological and psychological reactions such as alterations in cardiovascular responses, breathing, and anxiety to specific sound environments. Ultimately, medical outcomes, such as the need for pain or sleep medication or the time for recovery, and their relation to particular noise measures must also be examined. Only then will it be possi- ble to determine the appropriate noise interventions and mit- igation for health and wellness promotion in the hospital soundscape.
Our findings indicate that many staff members perceived noise as a problem that may contribute to stress symptoms. More research is needed to correlate self-reported stress with physiological reactions and to understand the role of the acoustical and other environmental conditions on occupant response. The sustained sound pressure levels measured were generally not sufficiently high to cause hearing loss. However, high intensity sound peaks were common and war- rant concern, particularly since the effect of noise peaks on hearing loss is less well understood. We found that modifica- tions to the acoustical environment such as added absorp- tion, improved sound isolation, and decreased levels of back- ground noise were positively perceived by staff and patients. We are currently pursuing additional research on how these and other improvements to the environment might impact both psychological and physiological response. The sound environment is complex and a detailed description of its time and frequency characteristics is also necessary to fully under- stand and prevent its negative impact.
Our findings raise concerns about oral communication in hospitals since the overall loudness and spectral shape of the background noise may make understanding speech diffi- cult. The typical speech level for communication between two people is around 50–55 dB(A) and a signal-to-noise ratio of 15 dB is generally necessary for clear communication. The measured background noise levels in our studies range from 50–70 dB(A) suggesting that the staff may need to routinely raise their voices in order to be heard and understood. The importance of good speech intelligibility cannot be under- stated. It is paramount throughout the hospital that speech must be clearly understood to reduce the possibility for med- ical errors. The issue of speech intelligibility, however, must be balanced with the concept of providing privacy for
patient, depending on time of day.
Future work should also consider the differences in exposure levels
conditions with overall levels resembling hospitals.
between patients and staff.
Conclusions and further work
Evaluating the Hospital Soundscape 27