Noise Machines: Are They Safe?
The other day my friend mentioned her baby wakes up in the middle of the night when her sound machine turns off. I asked her why she had her noise machine turn off in the middle of the night and she told me that she had heard it wasn’t safe to have it on all night.
I was shocked, I was a doctor- how did I not know this?! So I did a little digging and found an article written by a number of doctors including one I worked with in medical school entitled “Infant Sleep Machines and Hazardous Sound Pressure Levels” in the Journal of Pediatrics in 2014 (Hugh, S., et al.).
I found out I was not using a sound machine in a “safe” way. I personally started using a sound machine after a recommendation from some websites and friends, when my little one started going to sleep at 7:30 pm and my husband and I wanted to watch TV, cook, bang pots and pans and talk at a normal sound level. She has been sleeping fantastically with the sound machine and I never thought anything of it.
As the research article states, there are plenty of sleep consultants and websites that advocate for the use of noise machines, but nobody has researched the potential harms. Sound machines, for those of you who don’t know, are machines that parents use that provide a background noise that can include white noise, a shhhhh sound, the sound of waves or thunder and so on. They are used to block outside noise and/or to soothe a baby to sleep.
This study took 14 different sound machines and placed them on the highest volume at 30 cm, 100 cm and 200 cm from a machine that measured the output at those distances. The distances were chosen to mimic the placement of a noise machine in a nursery; 30cm being on the crib bed rail, 100cm being next to the crib on a table and 200cm being across the room. The risk that these researchers were determining is whether the output of these machines is loud enough to be considered a risk for noise-induced hearing loss.
For adults, the workplace noise limit is 85dBA (A-weighted dB) for an 8-hour exposure. While in the Neonatal ICU, the safe exposure limit for sound has been determined to be 50 dBA averaged over 1 hour when taking into account a baby’s smaller ear canals. 13/14 noise machines were able, at maximum sound, to create sounds greater than 50dBA. With these results the researchers concluded that to ensure safe usage of noise machines parents should:
1) Place the sound machines as far away from the crib as possible.
2) Play the sound machine at a low volume
3) Use the sound machine for the shortest amount of time.
While these are very good suggestions, there were limits to this study including the fact that they only measured the output of the machines at maximum volume, we are unsure of the long term effects of loud noise on the infant ear canal with regard to speech and auditory development, we don’t know if white noise, in and of itself, is detrimental to the child, and we don’t know with certainty exactly how long is safe for a sound exposure.
With that being said, I am trying to change around my little one’s exposure to the sound machine to meet the above suggestions but I am also hoping there will be more studies that can address the limitations of this research.
What have you heard about sound machines whether online or from a doctor or from your friends?