In recent years, a growing number of parents have been using sleep sound machines to produce white noise designed to soothe babies to sleep; however, researchers now warn that these noise machines may pose a risk of serious hearing damage for infants.
In a study published last week by the medical journal Pediatrics, researchers tested various sleep machines and found several produced sounds louder than the recommended limit for infants. Some even produced noise louder than what is recommended for adults.
Researchers from the University of Toronto, Canada, tested 14 different infant sleep machines (ISM), which produce ambient white noises. The machines are used to mask other sounds within and outside the room.
Dr. Blake Papsin and his team of researchers measured noise levels from distances of one to three feet from the machine. One foot resembles the typical distance from an infants head to the crib rail. Three feet is the equivalent of the distance across the room.
The maximum sound level at one foot away was greater than 50 decibels, the equivalent of the recommended noise limit for infants in a hospital nursery. Three of the ISMs produced noise greater than 85 decibels.
If the machines are played continuously all night to help the infants sleep, the noise would exceed occupational limits for accumulated noise exposure in adults. Researchers warn this may result in noise-induced hearing loss in the baby.
“ISMs are capable of producing output sound pressure levels that may be damaging to infant hearing and auditory development,” said Papsin.
The machines used in the study were not specifically named. However, the study indicated the machines are “widely available in the U.S. and Canada.”
Many parents use these machines, which produce nearly 70 different sounds, such as white noise, nature sounds, mechanical sounds and heartbeat sounds, to help soothe infants to sleep and cover up outside noise. The main goal is to increase uninterrupted sleep for both infant and parent.
According to study authors, the machines are encouraged on many parenting websites exactly for this reason. However, researchers warn the sounds are too loud for infants and may exceed the safe levels for adults.
Because the sounds are so loud, this may lead to damage to an infant’s hearing and hinder auditory development as the child ages.
Study authors are calling for several changes to ISMs. First, a manufacturer imposed limit to the maximum levels of sound produced by the machines, warnings concerning noise-levels printed on the devices, and they recommend that each device include a timer which would shut off the machine after a specified time limit.
Researchers also recommend to play the machine noises at low volumes and for short amounts of time. The noise produced should be no louder than a “soft shower.”
They advise parents to place the machines as far away from infants as possible, and especially never place them on a crib rail or in the crib itself.