White noise machines could harm babies' hearing: study

sleeping baby
sleeping baby 

Devices that produce soothing sounds in order to lull infants to sleep can be loud enough at maximum volume to damage their hearing, researchers have found.

Infant sleep machines emit white noise or nature sounds to drown out everyday disturbances to a baby’s sleep. The machines, sometimes embedded in cuddly stuffed animals, are popular gifts at baby showers and routinely recommended by parenting books and websites.

Some sleep experts advise parents to use these noisemakers all night, every night, to ensure the best rest for a newborn, while many parents say their babies become so used to the sounds of rainfall or birds that they will not nap without them.

But researchers at the University of Toronto evaluated 14 popular sleep machines at maximum volume and found they produced 68.8 to 92.9 decibels at 30cm, about the distance one might be placed from an infant’s head. And three of the machines exceeded 85 decibels, the workplace safety limit for adults on an eight-hour shift.

One machine was so loud that just two hours of use would exceed workplace noise limits.

At 1m from the cot, all the machines tested were louder than the 50-decibel limit set for hospital nurseries in 1999.

“These machines are capable of delivering noise that we think is unsafe for full-grown adults in mines,” said Dr Blake Papsin, senior author of the paper and chief otolaryngologist at the Hospital for Sick Children in Toronto.

Dr Papsin got the idea for this study, published in the journal Pediatrics, after a parent brought a portable white noise machine to the hospital, and its roaring sound was similar to a carwash.

“Unless parents are adequately warned of the danger, or the design of the machines by manufacturers is changed to be safer, then the potential for harm exists, and parents need to know about it,” said Dr Gordon B. Hughes, the program director of clinical trials for the National Institute on Deafness and Other Communication Disorders, who was not involved in the study.


But all is not lost – safe use is possible, the study’s authors suggest. “Farther away is less dangerous, a lower volume is better, and shorter durations of time … [these are] all things that deliver less sound pressure to the baby,’’ Dr Papsin said.

And Dr Marc Weissbluth, a paediatrician and author of Healthy Sleep Habits, Happy Child, said parents could still use the machines, with new precautions.

“If it’s too close or it’s too loud, this might not be healthy for your baby,” he said. But “a quiet machine that’s far away may cause no harm whatsoever”.

The study authors also recommended that manufacturers limit the maximum noise level of infant sleep machines. 

No specific brands, models or manufacturers were named in the paper, Dr Papsin says, "because the point is to start the conversation that every one of these is capable of damage if used inappropriately".     

Tips for safe use of white noise sleep machines

  • Place the machine as far away from your baby as possible.

  • Never put it in the cot or attach it to the cot rail.

  • Play it on the lowest volume and for the shortest duration possible.

  • Once your baby has fallen asleep, turn the device off.

- New York Times