Noise measurements were performed in eight patients' rooms, three intensive care units (ICUs) and one operating theatre at a large hospital (1300 beds). Daytime and nighttime L_Aeq in patients' rooms and in ICUs were higher than the recommended standards. The measured noise levels could interfere with normal sleep and could be dangerous for patients at greatest risk. The laminar flow ventilation system was the main source of noise in the operating room. The L_Aeq recorded during a surgical procedure was sufficiently high to mask speech communication.
The measurement of A-weighted sound pressure levels disclosed that staff activities were responsible for the loudest noises. Air-conditioning systems and electro-mechanical instruments were also important contributors to noise pollution in the hospital.