Blog

March 17, 2014

In the News: Sound Machines Effect on Hearing

Overall, our kids are pretty good sleepers.  We have our share of long nights with middle of the night awakenings, but overall we can't complain.  We have an established bedtime routine for each child involving bath time, stories, lullabies....and a sound machine.  Many sleep experts advise parents to use white noise to help soothe a fussy infant, and the noise-canceling effects are an added benefit.  So our kids, like many others, are lulled to sleep each night to the sound of white noise (in our case, we prefer the soothing sounds of ocean waves).  Our trusty sound machines are as essential to sleep for our kids (and hence for us parents as well) as anything else--be it the beloved blankie or pacifier.  And when we travel (bracing ourselves for expected sleep disruptions away from home) we check and double check to ensure the sound machines are packed!   

But, a recent study published in a major pediatric medical journal earlier this month has raised concerns that these sound machines are so loud they may cause hearing problems for children. The researchers compared the sound emitted at 30 centimeters (to simulate placement of sound machine on a crib rail), 100 centimeters (simulating placement near a crib), and 200 centimeters (to simulate placement across the room from the crib).

The results?

1. The sound machines, when turned up to maximum volume, were much louder than we may have realized.

• All 14 machines exceeded 50 dBA (which is the current recommended noise limit for infants in hospital nurseries) and all but one exceeded the recommended noise limit even from 200 centimeters away.  
• 3 of the sound machines, when turned all the way up and placed within a foot of infants' ears, would bombard infants with a noise level exceeding 85 A-weighted decibels (which is the safety limit set by the U.S. National Institute for Occupational Safety and Health for workers exposed for eight-hour stretches). 

2. Machines positioned closer to the crib are louder.

3. Longer durations of exposure to loud noises would likely cause worse effects on hearing. 

To be clear, nowhere in this study did anyone show that a child who fell asleep with the aid of a sound machine has suffered any damage to their hearing.  It's just raising concerns that these machines COULD negatively impact hearing.  And therefore, based on these findings, many are calling for manufacturers to limit the volume on infant sound machines to remove the "potential for harm."  Read this article for a nice critical review of the study.

So what should we do with this information?  You don't have to unplug your sound machine just yet, but we should consider modifying its use to help reduce the risk of any effect on our child's hearing.  Dr. Marc Weissbluth, a pediatrician and author of "Healthy Sleep Habits, Happy Child (my favorite book about sleep for children) recommends the following:

- Place the sound machine across the room from your child.

- Use a lower volume. 

- Use for short periods of time rather than all night long. Many sound machines have a "timer" feature.  The timer allows you to turn the machine on for a set amount of time, drowning out the ambient noises while your child is falling asleep, but then automatically shutting off (hopefully, once your little one is snoozing away).