Noise in an intensive care unit.

Patients and staff in hospitals are exposed to a complex sound environment with rather high noise levels. In intensive care units, the main noise sources are hospital staff on duty and medical equipment, which generates both operating noise and acoustic alarms. Although noise in most cases is produced during activities for the purpose of saving life, noise can induce significant changes in the depth and quality of sleep and negatively affect health in general. Results of a survey of hospital staff are presented, as well as measurements in two German hospital wards: a standard two-bed room and a special intermediate care unit (IMC-Unit), each in a different intensive care unit (ICU). Sound pressure data were collected over a 48 hour period and converted into different levels (L(AFeq), L(AFmax) L(AFmin), L(AF 5%)), as well as a rating level L(Ar), which is used to take tonality and impulsiveness into account. An analysis of the survey and the measured data, together with a comparison of thresholds of national and international regulations and standards describe the acoustic situation and its likely noise effects on staff and patients.