I sleep better with a white noise machine droning. Or in our case, an old iphone playing rain sounds on a continuous loop. In his 5 months of life, M has had very few nights without it. So when a news article about white noise machines potentially damaging baby hearing came along, mothers all across the internet had the huge PANIC button in their brain slammed with a non-informative hammer.
And by 'non-informative' I mean normal science reporting. News presenters with shabby understanding of science and even less desire to delve into the subject taking a single study and branding it as God's honest truth. But let's set aside the sensationalistic tendencies of the news to concentrate on the question of whether parents should worry about their white noise machine.
Should parents worry?
The answer is: no one friggin' knows. It's never been scientifically tested.
But what about this Dr. Blake Papsin and his research into sound machines? Well, what Papsin really tested was the loudness of sound machines. They found that almost all sound machines CAN be loud enough to damage hearing (>85dB), especially if the machine is within a foot of baby ears. In other news, I CAN drive my car over the speed limit.
I'm sure there are some parents who placed their sound machine in the crib or very close to the baby and turned it on to whatever loudness is default. Papsin's research says to move it further away and lower the sound. For some, this was probably a good cautionary reminder. I definitely kept my white noise machine at shower loudness (a la Dr. Karp). After reading the various news articles, I downloaded a sound meter app and found that I could probably reduce the loudness of M's white noise.
But even without the white noise, the sound meter was registering an ambient sound level of 50-53 dB. Was living near a highway in Seattle (with the pitter patter of rain) damaging to my little baby's hearing? According to Papsin, 50 dB of continuous noise was damaging. Since Papsin's work used sound meters and not baby ears, where did that 50 dB number come from?
Well, it seems that the 50dB (A-weighted... which means higher frequencies are considered 'louder' than lower frequencies) recommendation is from preemies in the NICU. A study found that putting ear muffs on preemies allowed them to sleep better. So the recommendation became to keep things as quiet as possible so that the babies sleep better. The recommendations included nurses wearing softer shoes and not writing on top of the incubator. There are also studies showing preemies being more likely to have hearing issues... but this has not been shown to be because continuous/loudness of noise in the NICU. <50 dB is a recommendation to improve sleep in preemies, not to keep them from hearing loss. So there's no scientific evidence showing that continuous noise >50 dB damages hearing in infants.
So are there any studies looking at what loudness of continuous sound harms baby hearing? No. The closest thing is continuous loud sound in utero (when still in the womb). Multiple studies have shown a correlation between babies in the womb being exposed to continuous loud sounds (85 dB for 8 hours a day) and a lot of bad stuff including hearing loss. So there's some evidence that noise levels that cause damage in adults also cause damage in unborn babies. That's not really surprising, though, is it? But that doesn't answer whether lower levels of continuous noise damage the hearing of already born babies.
Will this make me stop using white noise for M? No. Because though we do not know whether it's damaging his hearing, I do know it helps him sleep better. And better sleep equals better health. THAT is definitely known. On the other hand, I'm going to moderate the use of the sound machine somewhat by moving the machine further away and keeping the volume turned down.
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