Influence of the NICU on the Acoustic Isolation of a Neonatal Incubator.

Virginia Puyana-Romero,Edgar Jara-Muñoz,Daniel Núñez-Solano,Ricardo Hernández-Molina

doi:10.3389/fped.2020.00588

Abstract

The neonatal intensive care unit (NICU) is a very noisy place as compared to the intrauterine environment. To protect the neonate's health, international guidelines suggest avoiding noise levels above 45 dB in NICUs, but this recommendation is not normally met. The incubator acoustic isolation and the acoustic features of the NICU play important roles in determining the noise measured inside the incubator. In this study, the influence of two types of rooms, one with sound-absorbent covering and the other with reverberant surfaces, on the acoustic isolation of a neonatal incubator was evaluated using three acoustic isolation indexes: the level difference, the apparent sound reduction index, and the standardized level difference. Results show that the acoustic isolation of the incubator is very poor, with a level difference below 11 dBA at all frequencies. At 62.5 Hz, the level difference measured in both rooms exhibits a negative value, indicating that the incubator amplifies the noise coming from the NICU. Isolation of the incubator is poor, and the reverberation time (RT) of the containing room influences RT of the incubator, which is consequently higher when the containing room is reverberant; for example, the incubator RT in the reverberant NICU is 0.72 s higher at 500 Hz than that in a room with sound-absorbent covering.

Highlights

Numerous studies affirm that neonatal intensive care units (NICU) are noisy environments exceeding recommended sound levels [1,2,3] and that high noise levels have a significant impact on the health of preterm infants [4,5,6,7,8]
Measurements of reverberation time (RT), designated T30, were considered in this study; T30 is a measure of the time in which the Sound Pressure level (SPL) decays 30 dB, multiplied by 2
It is important to highlight that, the same configuration of the sound source and measuring equipment was used in both rooms, measured noise levels for frequencies from 250 to 4,000 Hz were higher in Room with reverberant surfaces (Nreverb) than they were in Room with acoustic absorbent covering (Nabs); this illustrates that a reverberant room amplifies noise levels

Summary

Introduction

Numerous studies affirm that neonatal intensive care units (NICU) are noisy environments exceeding recommended sound levels [1,2,3] and that high noise levels have a significant impact on the health of preterm infants [4,5,6,7,8]. The American Academy of Pediatrics uses the U.S Environmental Protection Agency noise standards for hospitals (45 dB during the day and 35 dB at night) and recommends avoiding sound levels over 45 dB in NICU environments [9, 10]. Measurements indicating increases in NICU noise levels have been published over the years, recent studies show that this is still an unsolved problem.

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Results

Conclusion