The "Sound of Silence" in a Neonatal Intensive Care Unit-Listening to Speech and Music Inside an Incubator.

Matthias Bertsch,Isabella Czedik-Eysenberg,Christoph Reuter,Lisa Bartha-Doering,Vito Giordano,Monika Olischar,Angelika Berger

doi:10.3389/fpsyg.2020.01055

Matthias Bertsch, Isabella Czedik-Eysenberg + Show 5 more

Open Access

https://doi.org/10.3389/fpsyg.2020.01055

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Abstract

Background: The intrauterine hearing experience differs from the extrauterine hearing exposure within a neonatal intensive care unit (NICU) setting. Also, the listening experience of a neonate drastically differs from that of an adult. Several studies have documented that the sound level within a NICU exceeds the recommended threshold by far, possibly related to hearing loss thereafter. The aim of this study was, first, to precisely define the dynamics of sounds within an incubator and, second, to give clinicians and caregivers an idea about what can be heard “inside the box.”Methods: Audio recordings within an incubator were conducted at the Pediatric Simulation Center of the Medical University Vienna. They contained recorded music, speech, and synthesized sounds. To understand the dynamics of sounds around and within the incubator, the following stimuli were used: broadband noise with decreasing sound level in 10 steps of 6 dB, sine waves (62.5, 125, 250, 500, 1000, 2000, 4000, 8000, and 16,000 Hz), logarithmic sweep (Chirp) over the frequency band 20 Hz to 21 kHz, singing male voice, singing, and whispering female voice.Results: Our results confirm a protective effect of the incubator from noises above 500 Hz in conditions of “no-flow” and show almost no protective effect of an incubator cover. We, furthermore, observed a strong boost of low frequencies below 125 Hz within the incubator, as well as a notable increase of higher frequency noises with open access doors, a significant resonant effect of the incubator, and a considerable masking effect of the respiratory support against any other source of noise or sound stimulation even for “low-flow” conditions.Conclusion: Our study reveals high noise levels of air supply at high flow rates and the boost of low frequencies within the incubator. Education of medical staff and family members as well as modifications of the physical environment should aim at reducing noise exposure of preterm infants in the incubator. Audiovisual material is provided as Supplementary Material.

Highlights

According to the World Health Organization (WHO), about 15 million babies are born premature every year with a ratio varying between 5 and 18% depending on the country of origin
Premature babies are constantly exposed to light and noise, and even if the American Academy of Pediatrics (AAP) (1997) suggests that the noise level should be less than or equal to 45 dB during the day and 35 dB during the night (American Academy of Pediatrics (AAP), 1997, p. 724), several studies have shown that the noise level within a neonatal intensive care unit (NICU) is much higher than recommended (Bess et al, 1979; Surenthiran et al, 2003; Altuncu et al, 2009; Berg et al, 2010; Matook et al, 2010; Milette, 2010; Salandin et al, 2011)
The results of this study show the protective effect of the incubator from noises in the mid- and high frequency range in conditions of “no-flow” from a respiratory support device, the strong boost of low frequencies below 125 Hz recorded within the incubator, the notable increase of higher frequency noises with open access doors, the resonance effect of the incubator, and the considerable masking effect of the respiratory support against any other source of noise or sound stimulation even in “low-flow-level” conditions

Summary

Introduction

According to the World Health Organization (WHO), about 15 million babies are born premature every year with a ratio varying between 5 and 18% depending on the country of origin. Surveillance monitors may increase the basic sound pressure level to 57 dB, and during medical visits, peaks of 82–114 and 117 dB may occur by opening or closing incubator doors or by the conversation between staff members (DePaul and Chambers, 1995; Marik et al, 2012; Philbin et al, 2017). Assume that these high sound levels may contribute to hearing damage or even hearing loss as diagnosed in 2–10% of preterm infants vs 0.1% of the general pediatric population (WroblewskaSeniuk et al, 2017). The aim of this study was, first, to precisely define the dynamics of sounds within an incubator and, second, to give clinicians and caregivers an idea about what can be heard “inside the box.”

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