Popular white noise machines may be too loud for babies

Out of 14 infant sleep machines tested, all were louder than the 50-decibel limit set by hospital nurseries, while two were louder than what's considered hazardous to adult ears in the workplace.

Mike Cohea/Brown University

It's no secret that parents of babies -- especially after the nights of interrupted sleep begin to add up -- go to great lengths to get their kids to sleep as many hours straight as possible. From dark rooms and swaddles to pacifiers and fans, any trick deemed safe is on the table.

Unfortunately, according to new research published in the journal Pediatrics, one popular tool may not be as safe as previously assumed: the steady hum of white noise machines.

Researchers at the Hospital for Sick Children in Toronto say that after testing 14 popular sleep machines, they found that every single one was capable of exceeding the 50-decibel noise limit recommended for hospital nurseries, while two actually exceeded the 85-decibel level deemed harmful to adult ears in the workplace. The researchers did not reveal which "popular" machines they tested.

The researchers tested the machines, which produce anything from a static hum to heartbeats or nature sounds such as waves and rain, at 30 centimeters, 100cm, and 200cm from the crib (so about 1 foot to simulate being next to a baby's head, 3 feet to simulate being next to the crib, and 6 feet to simulate being across the room). At 30 centimeters, the machines produced between 68.8 decibels and 92.9 decibels; at 100cm, all were still above the recommended 50-decibel limit set for hospital nurseries; and at 200cm, 13 of the 14 were still above that level.

In addition to the question of whether these machines overexpose babies to noise is the debate about whether steady noises during sleep instead of the real-life noises of neighbors, birds, and sirens may interfere in some way with the brain's ability to process sound. Does white noise simply mimic the babbling brook that our ancestors ideally slept near for millennia, or is its artificial steadiness somehow worse than the disruptive sounds of the modern world?

Until we know more, researchers like Dr. Ronald Hoffman of the New York Eye and Ear Infirmary of Mount Sinai are calling for "safe sound limits" to be set for manufacturers. Not involved in the study, he told Health Day that for now, parents should keep the volumes of these machines low and place them across the room from the crib.

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