Infant sleep machines: Hazardous for babies' ears?

laughing baby playing with mother
A new study has found that infant sleep machines can contribute to noise-induced hearing loss if played too loudly. Find out how use them safely. (istockphoto.com)

Today's guest blogger is Yell Inverso, Au.D, Ph.D, CCC-A, a pediatric audiologist at Nemours/Alfred I. duPont Hospital for Children.

As the mother of a 24 month old, I am well aware that when baby gets a good night's sleep, we all get a good night's sleep. And in talking with other new parents, we all agree that we'll work toward that goal –by any means necessary! One product on the market that I'm sure many parents have tried is the infant sleep machine (ISM), which can play music, natural sounds, or white noise. I personally use the "sleep sheep" type of ISM with my son. These products actually add noise to a baby's environment and can help soothe some babies while they fall asleep –and help them stay asleep.

But a study published online today in the journal Pediatrics found that ISMs can contribute to noise-induced hearing loss if played too loudly. As an audiology doctor, my desire to sleep is only outweighed by my concern for my son's delicate and tiny ears. The premise of these devices is a good one; however, only if they are used safely.

In the study, the maximum noise levels of 65 sounds in 14 different infant sleep machines were tested at three distances: 30 centimeters (to simulate placement on a crib rail), 100 centimeters (simulating placement near a crib), and 200 centimeters (to simulate placement across the room). All 14 machines exceeded 50 dBA, the current recommended noise limit for infants in hospital nurseries, and all but one exceeded the recommended noise limit even from 200 centimeters away.

Most ISMs on the market do not limit the volume enough so that they are safe at maximum volume.  So, as parents we have to adjust the way we use them. How far away the ISM is to your baby's ear plays a huge role in loudness, which means, even if the ISM comes with a bracket to mount it on the crib, don't do it. Keep the speaker as far away as you can where that it is still useful.  Additionally, don’t use it at full volume. If your child only responds to the sound when it is beyond 50 percent of full volume, use one that has a timer so that the length of play is reduced. The ISM I use shuts itself off automatically.

The study actually brings to light a larger concern than only the volume of sleep machines. There are many toys, music players, etc. marketed for infants and children that could cause noise-induced hearing loss. How can parents protect their child's ears in a world of technology and noise? Use your common sense and parental intuition for duration of use and never put anything on full blast.

If you want to know how we audiologists do it, I’ll let you in on a trade secret...sound-level meters! No, I am not recommending that everyone spend a thousand dollars and learn how to operate the real thing...there's an app for that! You can download sound level meter applications that range from simple to advanced and use them to get a rough estimate of whether a sound can be dangerous. But remember, a baby's small ear canal does a great job of amplifying sound, so always adjust the volume slightly lower than you would for yourself. 

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