Not much is as comforting or as peaceful as a sleeping baby, but getting a baby to sleep can sometimes be a challenge. Older parents may remember sitting their baby near the clothes dryer or running the vacuum cleaner to drown out environmental sounds that often wake a sleeping baby, like a barking dog or doorbell ringing.

Today, many parents use infant sleep sound machines, or ISMs, for the same reasons. The white noise seems to soothe babies, helps them fall asleep quickly, and helps them stay asleep, even when the dog starts barking.

But, a study a few years ago published in the medical journal Pediatrics raised questions regarding the safety of infant sound machines, and the potential harm to a newborn’s hearing.

The study tested the sound levels of 14 infant sound machines played at maximum volume. The volumes were measured at varying distances using correction factors to account for a 6-month-old baby’s ear canal.

What the researchers found was that the maximum sound levels at 30 cm (about 12 inches) were greater than 50 dB (A-weighted) for all devices, which is the current recommended noise limit for infants in hospital nurseries. Three machines produced output levels greater than 85 dB (A-weighted), which, if played at these levels for more than 8 hours would exceed occupational limits for accumulated noise exposure in adults and risks noise-induced hearing loss.

Even though maximum output levels were measured on infant sound machines tested in this study, most devices featured a volume control, which suggests that safer sound machine use is possible and that these machines may be used in accordance with recommendations for hospital nursery noise.

Furthermore, results from the study revealed that increasing distance from the sound machine results in a decrease in measured output level. This finding suggests that placing an infant sound machine at a distance more than 200 cm (6.7 feet) from an infant may also lead to safer use.

Though this study originally generated cause for concern, at a practical level, parents probably can safely use infant sound machines if they just keep a couple of things in mind.

• Purchase a sound machine with a volume control, and use the device at the lowest effective volume. This allows the baby to benefit from the white noise, but greatly reduces risk to their hearing.
• Place the machine several feet away from the infant, not in the crib next to their ears. The study suggested a safer distance is more than 200 cm from the baby, or about 6.5 feet away. Keeping the machine on a nightstand or dresser several feet from the infant’s crib should be relatively safe.
• Limit the duration of use to less than 8 hours if possible. Maybe utilize a timer than runs the device to help baby falling asleep, and then it turns off after 30 to 45 minutes.

All newborns have their hearing screened before leaving the hospital to determine potential deafness or hearing loss, and results should give parents comfort or inform them that they potentially need to follow up with a physician who specializes in infant hearing loss.

If your infant has normal hearing, using an infant sound machine safely may help the baby, and parents, ultimately get a good night’s sleep.

If you have any questions, please contact our audiologists and hearing aid specialists in Independence, Overland Park, Manhattan or Kansas City.