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Blog entry by Juli Reynolds

What are the negative effects of noise on premature babies?

Noise intervenes with a baby’s development.

The extent to which noise exposure has an effect on babies has crept into ever increasing focus in neonatal research in recent years. It is now known that excessively loud noise can have a negative impact on parameters such as blood pressure, breathing, heart beat and oxygen saturation. 

Sleep is interrupted, which in turn impedes development. The stress also increases energy consumption, which means that fewer calories go towards growth. Even in the long term, noise plays a role: the risks of hearing damage, developmental delays, periventricular leukomalacia and bleeding increase with a continuously high noise level.

Noise affects caregivers, too

In addition to risks to the baby, noise also affects people caring for the baby. A high noise level is associated with a higher error and accident rate and a generally lower standard of performance. A low noise level is therefore not only directly beneficial for a baby's development, but also indirectly beneficial in that it increases a caregiver’s ability to concentrate and deliver the best care possible to the newborns.

What is important when assessing the noise environment?

Everyday noise

A Swiss-French working group has researched the effects of everyday noise on the development of premature babies' tactile perception.3 Babies were randomly assigned to a loud group and a quiet group, with the noise coming from feeding pump alarms. According to the study, a high noise level not only negatively affects tactile perception but also sensory learning capacity in general. As such, the authors recommend avoiding unnecessary noise in intensive care units to the greatest extent possible, for example by adjusting the alarms on feeding pumps, which typically only indicate the fill level and are not vital.

Noise levels

In spite of these findings, noise is still often excessively loud in the majority of neonatal intensive care units. According to one study, the average NICU noise level throughout the day is Leq = 60.05 dBA and overnight Leq = 58.67 dBA,4 with premature babies exposed to frequencies greater than 500 Hz, 57 percent of the time. Other studies have demonstrated that simple actions often produce extreme levels of noise.5 Simply setting down an object on the incubator or knocking on the incubator can give rise to extreme levels of noise from 74 to 116 dBA, which can be compared to the level of noise produced by a hammer drill.

How can noise be reduced in the NICU?

Limiting environmental noise

Monitoring and reducing noise levels should be encouraged. The threshold for cochlear damage for adults is 80-85 decibels, and the newborn will have a lower threshold than this as the immature cochlear is more sensitive. In the nursery noises of this magnitude include closing portholes with a snap or placing bottles on the top of the plexiglass incubator.

Sound level recommendations for the nursery environment background noise should not exceed an hourly Leq 40-45 DB

Noise reduction tips

  • Avoid tapping on or writing on incubators, and close incubator doors and portholes carefully.
  • Have designated quiet times during the day (while also remembering to keep to limits at all times).
  • Encourage staff and visitors to talk quietly, and avoid talking over the infant in an open cot.
  • Move medical and nursing ward rounds away from the bedside or be mindful of speaking quietly.
  • Avoid banging bin lids.
  • Set monitor alarm limits and tone at appropriate levels and try to silence alarms as soon as possible.
  • Purchase equipment with a low noise criterion.
  • Monitor noise levels periodically to identify times and causes of high levels.

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