Analysis of noise in infant incubators and within neonatal intensive care units

Abstract

This paper presents an analysis of noise in infant incubators and within surrounding intensive care nurseries. Sound level measurements were obtained in several incubators in use at Portuguese hospitals and in their surrounding nurseries. In each incubator the microphone was placed on a crib mattress side by side with a present infant. All measurements were made with the incubator operating in a normally functioning mode with the typical surrounding daytime nursery noise. In the incubators the noise spectra fell within NC-52 (NCB-41/NR-52/RC-45) and NC-67 (NCB-59/NR-65/RC-61) and in the nurseries between NC-49 (NCB-45/NR-50/RC-47) and NC-68 (NCB-68/NR-71/RC-68). The Leq in the incubators were in the range 68-78 dB (56-68 dBA) when in the nurseries they fell between 68-77 dB (53-73 dBA). In the incubators the spectral energy was found to be concentrated mainly below 250 Hz. The values measured in the incubators revealed a decrease from those available in the literature for similar situations 30 years ago but not very far from the values found 20 years ago. The presence of high SPL's in most of the incubators and nurseries is attributed to the frequent use of loud sound alarms and to inadequate acoustical treatment of both the incubators and the rooms.