Elevated Sound Levels in the Neonatal Intensive Care Unit: What Is Causing the Problem? : Advances in Neonatal Care

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Original Research

Elevated Sound Levels in the Neonatal Intensive Care Unit

What Is Causing the Problem?

Mayhew, Kelli J. MScN, RN; Lawrence, Sarah L. MD, FRCPC (Pediatrics); Squires, Janet E. PhD, RN; Harrison, Denise PhD, RN

Editor(s): Dowling, Donna PhD, RN, Section Editors; Newberry, Desi M. DNP, NNP-BC, Section Editors; Parker, Leslie PhD, APRN, FAAN, Section Editors

Author Information
Advances in Neonatal Care 22(6):p E207-E216, December 2022. | DOI: 10.1097/ANC.0000000000000996
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Abstract

Advancements in neonatal intensive care now allow survival of infants born as early as 22 weeks' gestational age.1 Infants at this extremely low gestational age have immature central nervous systems, putting them at high risk of adverse outcomes due to excessive noise.2 Excessive noise can have negative effects on premature infants' sleep patterns, growth, and neurodevelopment.3 Maintaining a stable physiological state is important for the infant during this time of rapid central nervous system development.4–6 Evidence has shown that noise in the neonatal intensive care unit (NICU) can negatively affect the cardiovascular, respiratory, nervous, and auditory systems of the preterm infant. When exposed to sudden and loud noise, premature infants may exhibit changes in heart rate (tachycardia, bradycardia), respiration (apnea), blood pressure (elevated), oxygen saturations, and interrupted sleep patterns. In addition, excessive noise puts infants at risk of slow weight gain, elevated cortisol levels, decreased immunity, as well as increased risk of hearing impairment.7 Preterm neonates, who spend weeks in the NICU, are especially sensitive to noise and elevated sound levels because their auditory system is at a critical period of neurodevelopment.8,9 Research in the field of neonatal “developmentally supportive care” highlights that an environment free of excessive noise decreased neonates' oxygen requirements, days on respiratory support, and length of hospital stay, thus improving developmental outcomes.2,10

Survival rates for preterm infants (<37 completed weeks' gestation) have increased because of advancing technology in the NICU.5 However, the noisy environment in which preterm infants are cared for in the NICU may present an overload of sensory stimuli that can negatively impact their physiological responses and lead to behavioral changes.3 For example, sound levels in the NICU are reported to reach 120 decibels (dB) on a consistent basis.5,7 The American Academy of Pediatrics (AAP)3 and the World Health Organization11–13 have recommended maximum sound levels of 45 dB in the NICU. Existing research has focused on elevated sound levels in the NICU but has not systematically explored contributing environmental factors. Noise from sources such as alarms, phones, and bedside conversations adds to excessive noise in the NICU and may contribute to sensory overload.2 A sound level of 45 dB is approximately equivalent to the sound level of rainfall, whereas a sound level of 120 dB is approximately equivalent to a thunderclap or an ambulance siren. Noise in hospitals has been a topic of concern for more than 160 years, dating back to the time of Florence Nightingale, who admonished, “Noise is the absence of care.”14

REVIEW OF THE LITERATURE

A variety of strategies for decreasing sound levels in the NICU have been discussed in the literature.5,15–18 Sound-reduction strategies, such as promoting a “culture of quiet,” through education, reminders, environmental redesign, silencing alarms quickly, consistent scheduled daily quiet hour, and stationary noise meters with real-time visual feedback, are currently in practice in many NICUs globally.

Although the problem of elevated sound levels in the NICU has been documented in the literature and specific strategies have been trialed such as the “SoundEar” noise warning device, there is no consensus on a single independent intervention that can consistently resolve the issue, nor are there much data and discussion regarding contributing factors. Recommendations to guide the lowering of noise have not been widely implemented or adopted.5,19 Designing implementation interventions in the healthcare system requires detailed specification of the targeted change.19 The gap in knowledge is not only a lack of understanding that noise causing the elevated sound levels is potentially detrimental to the neonatal population in the NICU but also a lack in understanding of what are the contributing factors causing the problem, and what measures healthcare providers (HCPs) can take to provide developmentally supportive care to the preterm neonatal population.

The purpose of this current research was to measure sound levels in an NICU and to identify contributing factors associated with elevated sound levels by systematically exploring environmental factors. These baseline data can be used in the future to inform interventions to reduce noise.

What This Study Adds

  • This study provides a solid foundation of baseline sound levels in level III NICUs.
  • Contributing observational factors were identified to elevated sound levels.
  • Multivariate linear regression was used to determine demographic and observational data associated with elevated sound levels.
  • Elevated sound level data that can be used in future knowledge translation activities.

METHODS

Design

A descriptive, quantitative study was completed using observational and sound level measurements. Research ethics approval was obtained prior to the study initiation from The Ottawa Hospital Research Institute (OHRI) Institutional Approval for Ottawa Health Science Network Research Ethics Board (OHSN-REB) and from the University of Ottawa Office of Research Ethics and Integrity.

Sound measurements were recorded over 21 different time periods: 7 days, 7 evenings, and 7 nights. To best reflect the realities of nursing practice, the 21 time periods were divided into the following shifts: 7 day shifts from 0600-1400 hours; 7 evening shifts from 1400-2300 hours; and 7 night shifts from 2300-0600 hours. Boxplots were created to show the distribution of sound level measurements during the 3 shifts (days, evenings, and nights). Convenience sampling strategy was used, where the location of the sound measurements collected was based on proximity of the most acutely ill preterm infants. No identifiable patient or HCP information was collected. The observational method in this research was no concealment without intervention. The single researcher (K.J.M.) collected observational data simultaneously each shift with sound measurement for each period of time.

Setting

This study took place in a level III NICU in a perinatal center in Ontario, Canada. The unit has a total capacity of 24 infants in rooms A, B, and C. The study took place in room A, in which the infants are considered the most acutely ill (level 3), requiring intensive supportive care 1:1. This room is equipped with 9 isolettes and a specialized resuscitation bed. The Provincial Council for Maternal and Child Health Standardized Levels of Care definitions established the infant acuity levels (2013) and are assigned daily for all infants in the NICU on a scale of 1 to 3. Level 1 is assigned to infants 36 weeks' gestational age or more requiring continuing care (infants requiring oral or nasogastric feedings, and/or basic monitoring, phototherapy, management for a limited duration complication such as transient tachypnea of the newborn, antibiotic prophylaxis, hypoglycemia, and feeding difficulties). Level 2 is assigned to an infant 34 weeks' gestation or more and weight greater than 1800 g, with a mild illness expected to resolve quickly. These infants require special care and who are convalescing after intensive care (infants requiring nasal oxygen, oxygen saturation monitoring, initiation, and maintenance of peripheral intravenous [IV], gavage feedings). Level 3 is assigned to any infant (of any gestational age or weight) requiring mechanical ventilation support, including high frequency, and possibly inhaled nitric oxide. Infants in acuity level 3 are those who require comprehensive range of subspeciality consultants.20 Noise levels were measured in this 9-isolette open-bay room (defined as having multiple neonates cared for in a single room, in an open space, without fixed partitions or walls between them). Many of the infants (room A) in this NICU are extremely preterm and critically ill, often requiring 1:1 staffing. The staffing was equal for all shifts (day, evening, and night shifts = 13). The room is equipped with a warmer fridge, narcotics cabinet, computer central monitoring station, and one specialized bed for resuscitation, in addition to the individual equipment necessary for each infant. A stationary sound meter, named “SoundEar 2” (Inspiration Healthcare), is currently in operation in the room and is attached to the wall separating the two sides of the room. This sound meter displays 3 different colors (green, yellow, and red) for different sound levels (low, medium, and high), however, does not provide a visual display of the actual sound level in decibels. In this NICU, scheduled daily “Quiet Time” does not currently exist.

Data Collection

Data collection commenced March 2019 until May 2019.

Sound Level Data Collection

For sound levels, a portable sound meter, Casella model CEL 242-K, and the acoustical calibrator Casella CEL-120 were used for data collection. For each time period of the study, the sound meter was positioned in exactly the same location, midway between both sides of a partial wall, in an unobstructed location. The sound meter was attached to a tripod for a 360-degree sound recording on a portable stand to facilitate ease of movement in the case of an emergency. Sound levels were recorded every second for a total of 7 day shifts (0600-1400), 7 evening shifts (1400-2300), and 7 night shifts (2300-0600), resulting in 604,800 measurements of sound collected for analysis. Continuous sound levels during the preset periods, observational data collected about the general activity of the NICU, as well as the overall NICU patient census data were collected hourly during the time periods (total n = 21 time periods). Data from the first 2 day shifts were subsequently excluded from analysis, due to a calibration readjustment. This resulted in numerous empty cells in the output of sound levels, when sound levels were lower than the set 60-dB low parameter. For the remaining 19 shifts, the low and high parameters were set at 30 and 100 dB, respectively. As a result, data were available for analysis for these 19 shifts only. Sound was measured in decibels (dB), which is defined as the pressure of sound or the intensity of noise; this measurement uses a logarithmic scale, whereby an increase in 3 dB doubles the sound intensity.21 Therefore, a small increase in decibels represents a large increase in intensity of sound. For example, 10 dB is 10 times more intense than 1 dB, while 20 dB is 100 times more intense than 1 dB. The Casella sound meter was used and calibrated (CEL 242-K with acoustical calibrator Casella CEL-120). Sound data measurements were exported using proprietary software directly into Microsoft Excel.22

Observational Data Collection

Demographic and observational data were collected simultaneously to identify contributing factors to noise levels. Observational data collected included the infants' acuity level (degree of illness), number of neonates in the room, number of people in the room, number of alarms, number of IV pumps alarming, suctioning events, emergency events (eg, apnea and/or bradycardia requiring intervention such as positive pressure ventilation and/or suctioning), and any other events that contributed to noise levels (eg, accidently dropped objects such as a portable thermometer, a calculator, a capillary blood glucose testing machine). Events were counted and recorded hourly by hand on a data collection sheet designed for this study by the sole researcher (K.J.M.).

Data Analysis

Sound level data were analyzed by comparing mean differences and standard deviations of sound levels over different times of the 24-hour clock, shift type, and day of the week. Sound measurements were plotted over time, related to significant observational data collected. The parametric test analysis of variance (ANOVA) was used to compare means across the 3 types of shifts: days, evenings, and nights. Multiple linear regression analysis was used to determine demographic and observational data associated with elevated sound levels.

RESULTS

Sound Level Data

After excluding 2 shifts, 19 shifts were analyzed (n = 19). The stationary SoundEar 2 noise meter was activated and illuminated red for 90% of the time during data collection. The mean sound levels were recorded, as well as the maximum and minimum sound levels for each individual shift (see Table 1). The values presented are averaged from all the measurements of sound for each shift. Overall averages for each of the 3 shift periods (day, evening, and night) are calculated, providing maximum and minimum levels for each of the 3 shift periods. The mean sound level over all the shifts was 58.2 dB for day shift, 53.6 dB for evening shift, and 54.5 dB for night shift. The maximum sound level for any of the individual shifts reached for days, evenings, and nights was 83.5, 83, and 80.9 dB, respectively.

TABLE 1. - Sound Levels Measured in the NICUa
Day of the Week Mean (SD), dB Minimum Sound, dB Maximum Sound, dB
Day shift
1
2
3
4
5
6
7

Sun
Mon
Tue
Wed
Thu
Fri
Sat

...
...
58.3 (2.64)
57.6 (2.37)
59.5 (2.82)
58.6 (2.42)
56.9 (2.34)

...
...
50.6
49.4
49.8
50.2
50.9

...
...
71.4
77.2
83.5
78.6
81.6
Average 58.2 (2.4) 50.2 78.5
Evening shift
1
2
3
4
5
6
7

Sun
Mon
Tue
Wed
Thu
Fri
Sat

56.6 (3.53)
54.1 (2.65)
53.7 (2.32)
55.5 (2.34)
51.0 (2.71)
51.6 (2.25)
52.7 (3.67)

47.1
48.2
49.0
47.6
47.8
48.3
48.9

76.1
83.0
81.1
78.9
76.2
81.3
77.1
Average 53.6 (2.8) 48.1 79.1
Night shift
1
2
3
4
5
6
7

Sun
Mon
Tue
Wed
Thu
Fri
Sat

54.9 (2.64)
57.1 (3.71)
53.8 (3.18)
52.8 (3.44)
52.3 (3.19)
55.7 (2.95)
55.0 (3.11)

51.8
48.9
47.8
49.2
47.9
53.2
51.4

80.9
75.3
76.3
78.6
73.0
75.6
80.6
Average 54.5 (3.1) 50.0 77.1
Abbreviation: NICU, neonatal intensive care unit.
aBased on shift, day of the week, and reported in mean (dB). Day shift data 1-2 excluded because of parameters not captured by sound meter. Data analysis reported for 19 different shifts (n = 19). Day shift: 0600-1400; evening shift: 1400-2300; night shift: 2300-0600. Timing of the shifts reported by the 24-hour clock.

The range of weekday sound levels varied from 47.1 to 83.5 dB. Weekend sound levels ranged from 47.1 to 81.6 dB. For all time periods, the maximum and minimum sound levels were above the AAP recommendation of 45 dB. Figure 1 illustrates the average sound levels for each shift type (day, evening, and night). Figure 2 represents the average shift-specific maximum sound levels in relation to the AAP-recommended sound level.

F1
FIGURE 1:
Boxplots of sound levels (dB). Boxplots showing the distribution of sound level measurements during the 3 shifts (days, evenings, and nights). IQR indicates interquartile range. Data reported as medians and IQR. The top of the rectangle shows the third quartile (Q3), the horizontal line near the middle shows the median, and the bottom line shows the first quartile (Q1). The vertical line extending from the top of the rectangle shows the maximum value within 1.5 * IQR, and the vertical line from the bottom indicates the minimum value within 1.5 * IQR.
F2
FIGURE 2:
Sound levels. Horizontal red line in the middle of graph depicts AAP recommendation of maximum sound level of 45 dB. Results reported as mean sound levels. AAP indicates American Academy of Pediatrics. Standard error ± days 4.0; evenings 2.5; nights 2.5.

Observational Data

It was observed that there were many people, including infants, HCPs, parents, and visitors in the NICU every shift. The number of people in the room was continuously fluctuating throughout each period of time. The number of people in the room ranged at any given time from 7 to 34. It was observed that monitor alarms were often not being silenced quickly, as they were frequently alarming for greater than 3 minutes. Examples of recurrent sounds recorded were ventilator alarms (73 dB total recorded sound during the alarm), cardiac monitor alarms (60.2 dB), and central monitor alarms (a single computer monitor that visualizes each of the other cardio/respiratory alarm tracings of each individual infant in the unit; 75 dB) (see Table 2). Continuous sounds such as the hum generated from a closed blanket warmer reached 57.3 dB, and sound measurement while the blanket warmer door was being opened and closed on one occasion was recorded at 72.2 dB. Daily portable x-rays generated sound levels of 66.9 dB. Sound level generated from the hum of the “Medela” milk warmer was 66.7 dB. During each shift, objects were dropped randomly in the room; for example, a portable thermometer, a capillary blood glucose monitoring machine, or a calculator. This sudden noise created a recorded sound level of approximately 80.5 dB.

TABLE 2. - Summary of Observational Data Collected Each Shifta
Shift Dayb Mean Number People Mean Number Alarm Events Mean Number of IV Pumps Mean Number of Ventilators Mean Number CPAP Mean Number of Emergency Events Mean Number of Suctioning Events
Tue 23.3 14.5 16.2 6.0 0.8 0 0.2
Wed 15.4 17.6 21.1 5.0 0 0.3 0.8
Thu 16.6 17.4 17.0 4.0 0 0.3 0.9
Fri 17.7 42 16.0 4.0 2.0 0.3 0.6
Sat 20.3 23.9 17.0 4.0 2.0 0.4 0.3
Grand mean 18.7 23.1 17.5 4.6 1.0 0.3 0.6
Shift Evening Mean Number People Mean Number Alarm Events Mean Number of IV Pumps Mean Number of Ventilatorsc Mean Number CPAP Mean Number of Emergency Events Mean Number of Suctioning Events
Sun 12.8 16.0 4.0 0.0 4.0 0.0 0.1
Mon 17.3 20.3 6.1 0.0 2.7 0.2 0.1
Tue 11.4 20.6 5.0 0.0 2.0 0.0 0.2
Wed 9.6 19.0 3.0 0.0 1.0 0.0 0.0
Thu 9.0 17.3 3.0 0.0 2.0 0.0 0.1
Fri 13.6 18.3 8.1 0.0 2.4 0.3 0.2
Sat 14.8 17.5 5.0 0.0 3.0 0.0 0.0
Grand mean 12.6 18.4 4.9 0.0 2.4 0.1 0.1
Shift Night Mean Number People Mean Number Alarm Events Mean Number of IV Pumps Mean Number of Ventilatorsc Mean Number CPAP Mean Number of Emergency Events Mean Number of Suctioning Events
Sun 13.3 22.2 10.1 4.0 1.0 0.1 0.5
Mon 10.7 18.1 12.0 5.0 1.0 0.0 0.7
Tue 12.6 26.7 7.0 4.0 1.0 0.0 1.0
Wed 13.9 25.1 10.1 3.0 3.7 0.1 0.7
Thu 13.7 23.8 3.0 0.0 4.0 0.1 0.0
Fri 11.9 22.6 4.0 4.0 2.0 0.0 0.5
Sat 10.4 17.5 6.0 0.0 3.0 0.2 0.2
Grand mean 12.4 22.3 7.5 2.9 2.2 0.1 0.5
Abbreviations: CPAP, continuous positive airway pressure; IV, intravenous.
aData calculated and presented as means.
bDays Sunday and Monday of day shift excluded because of missing data. Day shift: 0600-1400 hours; evening shift: 1400-2300 hours; night shift: 2300-0600 hours.
cThe timing of the different shifts is reported by the 24-hour clock.

Results of Synthesis

Simultaneous multiple linear regression analysis was conducted to determine which factors were statistically associated with sound levels in the NICU. A summary of the simultaneous multiple linear regression analysis of the noise on the 5 variables is given in Table 3. The variables entered were number of people, number of neonates, infant acuity, number of alarms, and shift type. The final model had an adjusted r2 of 0.145, meaning our model explained 14.5% of the sound levels in the NICU. The multiple linear regression model was statistically significant (F = 16,445.629; P <α .001) (see Table 3). Specifically, there was a statistically significant positive correlation between elevated sound levels and the number of people in the room (r 48 = 0.35; P <α .001). There was a statistically significant pattern of mean sounds during the day shift (83.5 dB) as compared with the night shift (80.9 dB; 95% confidence interval, 0.126-0.314 dB; P <α .001). It was demonstrated that for each 1-point increase in infant acuity, there was an increase in sound level of 0.15 dB (see Table 3). All the variables significantly predicted sound levels in the NICU when all 5 variables were included. Type of shift was used to compare the 3 group means of shift. The sound levels based on shift type were compared using ANOVA for which a formal comparison of repeated measures indicated a statistically significant difference between the groups (F2,559281 = 45,750.528; P <α .05). The ANOVA was used to compare the sound levels within the 3 shift types; 45,750.528 is the F statistic, with 2 degrees of freedom for the numerator and 55,9281 degrees of freedom for the denominator (expressed as the subscript in F2,559281), that is calculated from the data. Here, sound within the different shift types has statistically significantly different levels (see Table 4).

TABLE 3. - Multiple Linear Regressiona
Variable b β SE r 2 P
Intercept 53.273 ... 0.043 ... ...
Number of people 0.253 .350 0.001 0.360 <.001
Number of neonates −0.102 .049 0.005 0.094 <.001
Infant acuity 0.155 .057 0.006 0.150 <.001
Number of alarms 0.006 .038 0.000 0.147 <.001
Shift type –0.691 –0.120 0.009 0.145 <.001
aSummary of simultaneous multiple linear regression of the noise on the 5 variables (number of people, number of neonates, infant acuity, number of alarms, shift type). Dependent variable is noise. Overall r2 = 0.145; adjusted R2 = 0.145; F = 16,445.629 (n = 19).

TABLE 4. - ANOVA Analyzing Noise Between Shift Typesa
Shift df Mean N Sum of Squares Mean Square F Statistic P
Day 2 58.1753 145,302 ... 3,384.37 ... .001
Evening 2 53.6330 176,698 ... 2,876.49 ... .001
Night 2 54.4642 237,284 2,966.35
Between groups (combined) 2 ... ... 1,847,925.90 923,962.949 45,750.528 .001
Within groups 559,281 ... ... 11,295,059.1 20.196 ... .001
Total 559,283 ... ... 13,142,985.0 ... ... ...
Abbreviation: ANOVA, analysis of variance.
aANOVA includes the 2 factors: shifts (day: 0600-1400; evening: 1400-2300; nights: 2300-0600) and noise levels.

DISCUSSION

The findings of this study showed that sound levels during each shift (day, evening, and night) in this NICU exceeded the AAP recommendations 90% of the time. On average, sound levels were 14 times louder than recommended, roughly the equivalent of the sound of a constantly running vacuum cleaner. As the number of neonates and HCPs in the NICU increased, the sound levels increased. It was observed that the higher the acuity of the neonate, the more HCPs involved and the higher the sound generated at the bedside. Although the difference between the maximum day shift and minimum night shift mean sound levels was 2.6 dB, an increase in 3 dB is a doubling of sound intensity.

Previous research suggests sound-reduction strategies for promoting a quiet NICU include environmental redesign, reminders, scheduled daily quiet time, ongoing education, silence alarms quickly, and staffing ratios.5,18,17 In addition, sound levels have been found to be higher in level III NICUs than in level II NICUs,24 potentially related to the increased medical technologies utilized in the complex NICU environment.23 In level III NICUs, there are more HCP conversations, lifesaving interventions, alarms from cardiopulmonary instability, IV pumps, and medications requiring a second nurse to verify dosage. Human factors contributing to elevated sound levels in this study include the volume and quality of speech, frequency and force of opening and closing doors, and failing to silence alarms quickly. Environmental factors contributing to elevated sound levels in this study include hospital-wide loudspeaker announcements, portable x-ray machines being wheeled into rooms, and recurrent, continuous, and sudden unexpected sounds, such as dropped objects or chairs being pulled across the floor. In addition, open-bay room designs (where multiple infants are cared for in a large room vs single-family rooms where one infant is cared for individually)15 may also contribute to overall noise levels. Newer NICUs have often been redesigned with individual single patient rooms and sound-dampening technology, which likely contribute to lower sound levels. Single-family rooms in the NICU have been shown to expose infants to less noise and light and provide a more controlled, private environment, which may encourage parental presence and involvement in care15 and reduce length of stay.24

Understanding the relationship between elevated sound levels and contributing factors in the NICU can lead to identifying steps necessary to reduce consistently elevated sound levels. In addition, examining best practices, policies, and interventions employed in other NICUs, in other hospitals, and in other countries can help us understand what can be done at the local level. While not all NICUs have the same infant population, acuity level, capacity, or environmental layout, the end goal of sound reduction is universal for all NICUs and can also be applied to other areas of the hospital environment.

Effective ways to reduce sound levels and promote an environment that will optimize the neurodevelopment of preterm neonates are key to improving neonatal outcomes. Evidence from this study, as well as previous studies, shows that baseline sound levels are consistently higher than those recommended5,17,25 despite the knowledge of adverse effects of elevated sound levels in the NICU. This may adversely affect not only neonatal outcomes but also HCPs working in the NICU. Silva et al26 conducted a survey of HCPs, including nurses, physicians, physiotherapists, and technical assistants, and reported that 77% of HCPs considered the NICU too noisy. Despite this perception, the results in our study show behaviors that seemed to demonstrate a lack of awareness of what they might be doing to decrease noise; for example, behaviors such as using a loud conventional voice at the bedside, failing to promptly silence alarms, and loudly opening and closing doors. Some HCPs may view their work environment as part of their personal space and not that of the sensitive environment of the developing preterm neonate. Our professional colleagues need reminders and education to help them understand the importance of quiet in the NICU and how the noise affects the delicate developing neonatal brain.

During data collection, it was observed that the sound-activated noise monitor, the “SoundEar 2,” used in this NICU for greater than 10 years, was illuminated red 90% of the time, indicating that noise exceeded 45 dB for almost the entire period. It was evident that this near-constant visual display of the red SoundEar failed to promote behaviors for noise reduction or action by the NICU staff. One potential reason for this lack of attention is the model and age of the equipment. Some newer, more advanced technological “SoundEars” display a real dB value, which allow HCPs to observe an actual change in the dB number based upon their behavior, thus providing positive feedback for their effort, even if the value remains above the recommended 45 dB. A continuous red “SoundEar” does not provide this same positive feedback; consequently, newer up-to-date technology could be used to optimize the NICU environment. Short-term solutions for the reduction of sound levels include behavioral strategies of reminders for silencing monitor alarms, using a quieter conversational voice at the bedside during care and during multidisciplinary rounds, and scheduling of regular and daily quiet time.5,19,27–29 Laubach and colleagues,18 however, state that reminders for HCPs need to be repeated and ongoing in order to reduce excessive noise in the NICU. Wang and colleagues17 also reported that improvements are small, and on their own, reminders have limited sustained effectiveness. According to Presseau et al,19 to promote successful behavior change, educational interventions should include collaboration of HCPs, families, and visitors when developing strategies for practice change.

A key strength of this study was the comprehensive and simultaneous collection of sound and observational data. To the best of our knowledge, this is the first research to bring together the existing literature that explores elevated sound levels and observational data with multivariate analysis. The findings of our study provide a baseline for knowledge inquiry into the identified problem of sound levels in the NICU and an understanding of some of the contributing factors.

Limitations include a large number of variables present in the NICU environment that were not observed or evaluated and which could potentially alter the context of sound levels. For example, not recording the sound levels within the isolette and not recording sound levels in other rooms (rooms B and C) within this NICU potentially limit the research findings. However, some infants were in radiant warmers rather than isolettes during the study and thus potentially affecting the level of sound to which they were subjected. Research comparing 3 models of incubators concluded that preterm infants are exposed to noise levels exceeding international guidelines (produced continuous equivalent noise levels of 53.5-58 dB and reduced external noise by 5.2-10.4 dB), although such levels comply with the limit set by the standard recommendation.30

Future sound-reduction strategies should include adapting evidence to the local context, assessing barriers and facilitators to practice change, and including all HCPs and families in planned design and implementation of interventions.31

-
What we know:
  • Sound levels in the NICU exceed national recommendations of 45 dB.

  • Excessive noise negatively impacts premature and sick neonates in the NICU.

  • Sound levels need to be lower to promote an optimal environment of growth and neurodevelopment.

What needs to be studied:
  • Further research, focused on effective sustainable interventions, to reduce sound levels in the NICU.

  • Research could include an evaluation of the long-term effect of noise education protocols on the neurodevelopment of preterm infants.

What can we do today: Short-term solutions:
  • Silencing monitor alarms quickly.

  • Using quiet conversations at the bedside during care and during multidisciplinary rounds.

  • Scheduling quiet time daily.

  • Assignment of “Noise Monitors.”


Long-term solutions:
  • Environmental redesign.

  • Use of sound-absorbing materials.


CONCLUSION

This study explored the sound levels in one open-bay NICU, and our findings reinforce the knowledge that sound levels are consistently above the AAP recommendations of 45 dB. Multiple factors were identified that contributed to the elevated sound levels in our NICU, including HCPs talking in loud conversational voices at the bedside and not promptly silencing the monitor alarms, the number of people in the room, number of neonates in the room, number of alarms, infant acuity, and shift type. Sound level reduction should be prioritized in NICUs to promote developmentally supportive care2 and optimize the environment using a combination of knowledge translation strategies.29 Sustaining a quiet NICU environment depends on engagement of all HCPs and families, which will promote premature infant outcomes.

References

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Keywords:

neonatal intensive care unit; neonates; noise; preterm infants; quiet time; sound levels

© 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the National Association of Neonatal Nurses