Systematic review of environmental noise in neonatal intensive care units.

Aim: To systematically review the literature on noise exposure within the neonatal intensive care unit/special care nursery settings, specifically to describe: noise characteristics, sources of noise and ways of measuring noise.

Methods: Systematic searches were conducted through databases Medline, Embase and PubMed. Studies were included if they met the inclusion criteria (1) reported noise characteristics; (2) reported noise exposure measurements; (3) in the neonatal intensive care unit/ special care nursery settings. Methods and key findings were extracted from included studies. Quality analysis was done using a modified version of the Newcastle-Ottawa Scale.

Results: We identified 1651 studies, screened 871, reviewed 112 and included 47. All reported NICU average equivalent sound levels were consistently louder than recommended guidelines (45 dB). The most consistent association with higher sound pressure levels were noise sources grouped under people congregation. Half of the studies did not use measuring devices adhering to international sound level meter (SLM) standards.

Conclusion: All NICUs exceeded recommended accumulative sound levels. People were the most consistent source of noise. Sound pressure levels need to be consistently measured with devices adhering to international SLM standards in future studies.