Sound pressure levels in India's Neonatal Intensive Care Unit exceed safety limits, risking hearing impairment in babies

This study showed that existing Neonatal Intensive Care Unit environment has very high sound pressure levels. This can cause hearing impairment, sleep disturbances, somatic effects, impaired auditory perception and affect emotional development in babies.

Journal of Neonatology
Year : 2005, Volume : 19, Issue : 2
Online ISSN : 0973-2187. Print ISSN : 0973-2179.

Evaluation of Sound Pressure Level in Neonatal Intensive Care Unit

Authors: Gupta Vivek, Soodan K.S., Gupta Girish, Sondhi Vishal, Nair MNG
Neonatal Division, Department of Pediatrics, Armed Forces Medical College, Pune - 411 040, India [email protected]

Safe acoustic in NICU environment is extremely crucial for the best outcome of the neonates. This study was designed to answer the research question of the sound pressure levels (SPL) produced by various relevant variables in NICU. The study was conducted in a NICU of a tertiary care hospital. Sound level meter – 2231 was used for measuring SPL. At the beginning SPL of external enviornment and vacant NICU were measured. Sound produced by various equipments, appliances, personnel and other events in NICU was measured at various distances from the source. 3-5 readings were recorded for each event. Data was analysed statistically for significance. SPLs in the vacant NICU was found within the normal limits. Baseline average SPL in the NICU was 51decibels. Average SPL in the NICU remained between 60-80 decibels. Maximum recorded SPL in the NICU was 102 decibels produced by falling of katori. This study showed that existing NICU environment has SPL in the range far from safety, at times in the dangerous zone.

The Neonatal Intensive Care Unit (NICU) environment is a crucial determinant for the best outcome of the neonates (1). NICU personnel and instruments create noises of various decibels. The American Academy of Pediatrics, Committee on Enviornmental Health, recommends a maximum safe noise level of 45 decibels in the NICU (2). If there is increased sound beyond the recommended levels, it is likely to produce various impairments in the neonates viz. Hearing impairment (3,4,5), Sleep disturbances, Somatic effects, impaired auditory perception and emotional development. Goal must be to prevent emergence of noise in NICU rather than treating the infants with impairments. To achieve this goal, it is essential to know the sound pressure levels (SPL) produced by various instruments and personnel. The frequencies and individual susceptibility are also contributing factors for the harmful effects (6). Chang et al showed that 4994 peak noises were recorded during 48 hour observation period (7).

Till now no well designed research work has been done in India, addressing to the noise production in NICU. Hence, the present study was planned to address the research question of evaluating sound levels in the NICU generated by men and machine.

Aims and Objectives
1. Assessment of noise levels in the NICU.
2. Identification of noise sources.

The result of this study showed that most of the times SPL in the NICU remained above the recommended safe limit of 45 decibels. Average SPL in the NICU remained between 60 - 80 decibels. Maximum noise recorded in the NICU was 102 decibels produced by falling of katori. It is more than double of recommended safe level. The following sources produced SPL > 80 decibels viz. alarms of ventilator, radiant warmer, oxygen concentrator, pulse oximeter, CVT; crying neonate, dragging of dustbin and iron stool and falling of chair and opening of oxygen cylinder. These SPLs are far from satisfactory and may cause annoyance, hearing loss, pain and distress to the neonates. Can we allow our beloved neonates to suffer? Never. Therefore, in view of the observed SPLs in the study, which fall in the dangerous zone, it becomes very important to develop methods and technologies to reduce the noise levels in the NICU and prevent sound related morbidity and mortality of neonates. Therefore, this study is likely to be proved as a landmark Indian research which will change the attitude of NICUs by making them more humane in general and audition supportive in particular.


To fulfill the objective of keeping the sound levels within the normal range following NICU practices are recommended viz. turning down volume of the alarms of various instruments to the minimum, use of visual alarms instead of audible, keeping the working instruments at appropriate distance from the neonate, proper periodic maintenance of instruments and appliances, gently closing the portholes of the incubator, complete or partial lining of the equipment with sound absorbent material, testing each new incoming equipments for SPL, incorporating, use of plastic bowls and trays, using rubber bumpers or pads for movable instruments and trolley, adjusting volume of telephones,, use of earplugs and earmuffs for the neonate, use of Central oxygen and suction, if not available then carefully opening the oxygen cylinder outside the main room and a system of regular noise assessment in NICU. Education and awareness about noise levels and their adverse effects on neonatal outcome, will bring in an attitudinal change with likely consequent decreased personnel conversation and conversation at low intensity inside NICU. It is also suggested that NICU architecture should be acoustically designed so as to absorb sound and NICU to be located in silent surrounding environment.

Published: 05 Oct 2005

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Journal of Neonatology