Sleep machines could impact infant’s hearing
TORONTO—White noise machines for babies that are becoming increasingly popular among parents may be putting the children at risk of hearing loss, a new Canadian study suggests.
If operated as sometimes suggested (with the device close to the child, on a loud volume, and running continuously), some of the machines exceed the noise limits occupational safety agencies have set for adults, the study noted.
“The effects, potentially, on auditory development and speech and language development are theoretical, at best,” said senior author Dr. Blake Papsin, otolaryngologist in chief at Toronto’s Hospital for Sick Children.
“There are animal models in rodents that show that this happens.
“But the whole concept of replacing periodic, lovely, incredibly complex environmental sound for the young, developing, processing brain with a babbling brook or [he makes the sound of static] is foolish to me.”
The study was published last week in the journal Pediatrics.
The idea for the study on infant sleep machines, as this line of products is called, came from a check Papsin made on a young child who had undergone surgery at Sick Kids.
A sleep machine was operating loudly when he walked into the patient’s room. The parents informed the startled Papsin that they had been told to use the machine by a sleep doula.
He left the room, and fetched one of his students and a sound level meter.
“In the room she records 85 decibels—the sound of a car wash,” Papsin said. “In the kid’s ear!
“To mask the noisy ward, which was probably 85 decibels itself.
“I said ‘I’m going to go study this. This is crazy,’” he added.
Papsin’s team bought as many different types of sleep machines as they could find, both from baby supply stores and online sources.
They found 14 different models which projected a variety of sounds, such as a heartbeat, rain, crashing waves, and white noise.
They tested each at its maximum volume, at three different distances: 30 cm (which would be the typical distance to a baby when devices are attached to the slats of a crib), 100 cm (which would be like a placement on a surface near the crib), and 200 cm (the equivalent of across the room).
Occupational health standards set 85 decibels of noise for eight hours as the limit for adult ears; after that point, hearing loss could occur.
For every three decibels over that limit, the allowed exposure time is halved. So at 88 decibels, the exposure limit is four hours.
No one has done studies to figure out what a safe exposure equivalent is for young children, nor is such a study likely to be done.
It would be considered unethical.
But because of the physical traits of an infant’s ear (the small ear canal amplifies higher frequency sounds), neonatal intensive care units have recommended that babies should not be exposed to more than the equivalent of 50 decibels averaged over an hour.
All but one of the machines, at all three distances, exceeded the 50 decibel level, Papsin and his team found.
The one exception registered 49.2 decibels—and then only at the 200 cm distance.
In fact, at 30 cm—in the crib—three devices emitted sounds over 85 decibels, with one hitting just under 93 decibels.
At the 100 cm distance, all the machines registered at 60 decibels and upward.
The sound levels ranged from 49.2 to 76.2 decibels at the 200 cm distance.
Papsin noted these sound levels were in addition to whatever noise they were being used to mask.
“Philosophically, have we come to this? Have we come to this as a society in 2014, that you need an app for cuddling your baby?” he asked incredulously.
“Maybe if the baby’s comfortable falling asleep to a heartbeat, go to the crib and grab them, put them against your chest,” Papsin said.
“Use the factory-installed one.
“Slow down here. Let’s have a conversation, society,” he stressed.
Papsin may not be a fan but many young sleep-deprived parents are.
They rave about the machines to friends, buy the machines for baby showers, and pass them on when their children outgrow them.