Pediatric Research: Too much noise a problem for premature babies was written by Dr. John Barnard who is the President of the Research Institute at Nationwide Children’s Hospital.
When I trained in pediatrics three decades ago, the neonatal intensive care unit was among the busiest areas in Vanderbilt Children’s Hospital.
We arrived sleepy-eyed at 6 a.m. and were greeted by bright fluorescent lights in two large, adjacent rooms filled wall-to-wall with critically ill, premature infants. Ventilators, vital for breathing in the smallest babies, welcomed us with a cacophony of loud, syncopatedpssst pssst pssst sounds.
The unit sounded like a factory assembly line, and we could easily judge just how collectively sick the babies were based on the decibel level of the ventilators, IV pumps and heart-rate alarms.
While this made it tough for us to wake up to a busy day, it was far worse for the babies who lived with this commotion day and night.
Research in the intervening years has taught us that stress caused by bright lights, loud, continuous noise and painful stimuli such as blood tests hurts the fragile, still-developing brains of premature infants. Noise, especially, is a concern.
Physical science and neuroscience have helped us understand the intersection of noise, sound and hearing in the human fetus and newborn. Although fetal hearing is not fully developed, research clearly shows fetuses hear sounds coming from outside their mother’s womb.
Imagine what they hear as they grow in an amniotic-fluid-filled uterus. Sounds are further muffled by the muscular wall of the uterus and the mother’s abdomen. Sounds outside and much closer — the mother’s voice and heartbeat — make up a fetus’ muffled acoustic world.
It is under these soft and subdued circumstances that important neural connections are made in the brain to create normal hearing.
Unfortunately, an infant born several months early does not have the luxury of this soothing, gradual acoustic introduction to the outside world. Immature neural circuits are unprepared to cope with the unfiltered noise of the intensive care unit.
The implications of excessive noise in premature infants are potentially serious. In the short term, it is undoubtedly harsh and stressful for critically ill, premature newborns. In the long term, excessive noise might abnormally wire neural circuits in the premature brain in a way that damages hearing and brain function for years to come.
Fortunately, research has helped us to understand the volume and quality of sound in the modern neonatal intensive care unit. As a result, the American Academy of Pediatrics has recommended sound levels be kept below 45 decibels — about the level of a normal conversation at home.
Despite this recommendation, research shows these sound levels are often exceeded.
Long ago, Florence Nightingale, the founder of modern nursing, said, “Unnecessary noise … is the most cruel absence of care which can be inflicted on either sick or well.”
Her wisdom has been confirmed by research that describes the critical nature that noise has on development of hearing and brain development.
I am happy to say many neonatal programs are making progress in reducing noise. For our own unit, despite the large number of critically ill babies, we have a much quieter and less chaotic space than the one in which I was trained.