Sound levels in a neonatal intensive care unit significantly exceeded recommendations, especially inside incubators

Abstract

Aim: This study measured sound levels in a 2008 built French neonatal intensive care unit (NICU) and compared them to the 2007 American Academy of Pediatrics (AAP) recommendations. The ultimate aim was to identify factors that could influence noise levels.

Methods: The study measured sound in 17 single or double rooms in the NICU. Two dosimeters were installed in each room, one inside and one outside the incubators, and these conducted measurements over a 24-hour period. The noise metrics measured were the equivalent continuous sound level (L_eq ), the maximum noise level (L_max ) and the noise level exceeded for 10% of the measurement period (L₁₀ ).

Results: The mean L_eq , L₁₀ and L_max were 60.4, 62.1 and 89.1 decibels (dBA), which exceeded the recommended levels of 45, 50 and 65 dBA (p < 0.001), respectively. The L_eq inside the incubator was significantly higher than in the room (+8 dBA, p < 0.001). None of the newborns' characteristics, the environment or medical care was correlated to an increased noise level, except for a postconceptional age below 32 weeks.

Conclusion: The sound levels significantly exceeded the AAP recommendations, particularly inside incubators. A multipronged strategy is required to improve the sound environment and protect the neonates' sensory development.

Keywords: Decibels; Incubator noise; Neonatal intensive care unit; Noise metrics; Sound levels.