Are there any dangers or downsides to white noise as a calming tool

Question

We find white nose to be extremely effective for soothing our 5-week old son. Loud white noise (60 decibels or so) will help soothe him when he is overtired and crying, and if we play soft white noise (40-50 db) near him as he sleeps he is much less likely to fully wake himself up when he stirs.

But I have a few concerns:

• Will hours of white noise a day cause hearing damage? We make sure that sustained volumes are always less than 60db which is below any level for hearing damage, but the temptation is to have it going whenever he is asleep and I can't find any data if long term, low volume of a constant sound can be detrimental to an infant's hearing.

• Will this become a crutch he will need to get to sleep even when he's much older? On one level that wouldn't be so bad since it is extremely easy to provide (just flip on an iPhone app). But I'd hate to make things more difficult for us down the line.

Anyone with experience or knowledge on this? The only study I could find exposed rats to 24/7 noise and predictably it delays their ability to recognize other sounds. But we obviously don't use it even close to constantly.

Answer 1

I'm not a doctor too, just an engineer, but:

• 60 dB can not damage your hearing. 85 dB for 8 hours a day is a safe limit for adults, and 60 dB is very very far from that.
• If you use the white noise for couple of tens of minutes, it is hard to believe it will cause any stress or psychological damage. I think any continuous noise is bad, if it is too loud and/or durates hours. White noise is natural noise, for example, if you lived next to a waterfall, you would be always listening to white noise :-).
• There is some research done on subject close to this, see for example http://scholar.google.com/scholar?hl=fi&q=white+noise+infant
• Don't worry if your child gets used to listening white noise when falling asleep. The same problem is with drinking breast milk or water from a bottle, telling stories, singing a song etc. It will take couple of days or maximum couple of weeks to get rid of that habit. For example, our child got a water bottle as a sleeping aid. It took couple of days to learn to sleep without it. Of course, those couple of days were disturbing :-).

Answer 2

I am neither a scientist nor a doctor, but I believe they spent 9 months listening to white noise (well, 4 months, at least) in the womb. And given that most of us have fallen asleep as infants with some form of noise (music box, radio, mom's lullabyes, mobile, etc). I doubt that short of dangerous DB levels there'd be any sort of harm from white noise.

(I also worked in offices that pumped in white noise 8 hours a day, so, at least OSHA thinks it's fine for us grown up folks)

Answer 3

I cannot speak to actual hearing loss, but the study you cite definitely suggests that you are right to be concerned (I believe you are talking about this study, the abstract doesn't really cover much, but it does seem to suggest that discerning sounds will be impeded by an excess of white noise).

That said:

1. White noise is incredibly effective at soothing babies, but this effectiveness decreases over time (according to "Best Baby on the Block" it is most effective for the first three months after birth (called the "forth trimester"))
2. Anything used in excess will become a crutch for your child to sleep. Now, in this case it is fairly innocuous — white noise is easy to reproduce and fairly harmless, but it will become a crutch if used excessively. It is always best to allow a child to fall asleep on its own.

In my particular case, we've used white noise and music to sooth the savage beast, but we always let our kids fall asleep "unaided" (not held, not falling asleep while feeding, only a moderate amount of noise in the background at most (note: we do not have a "quiet room", silence can also be a crutch)).

Your best bet to avoid crutches is to wait until the child is about to fall asleep and then put the child into the crib.

Answer 4

Intrauterine sound levels have been measured to run between 72dB and 88dB. For us, things start to sound loud at about 75db. Hearing damage will result from continued exposure to sound over 85dB. This makes it sound like babies are shielded, somehow, from sound levels that would bother or damage us.

However, inside the womb (unlike outside it) the middle ear is fluid-filled; the hearing mechanism is mostly through bone conduction and this results in large attenuation of higher frequency sounds -- 20-30dB. Fetuses are cushioned; babies are not. White noise is distinguished by having equal power at all frequencies.

Without further careful analysis of fetal hearing mechanics as compared with those of young babies, we should be wary of exposing babies to high noise levels. We're playing with fire here.

References

Noise levels and hearing loss

Intrauterine sound levels

Intrauterine hearing mechanisms: same as previous but with final number = 8899910

White noise: see Wikipedia article.

Answer 5

Lack of sleep is linked to behavioural disorders in children and a range of medical conditions in adults, including myocardial infarction and obesity. Lack of sleep increases hunger. I don't have any citations, but I'm a doctor and have attended plenty of lectures given by eminent professors in sleep studies. Also I think most of us would agree that we eat more junk when we're tired. I would be happier that my child sleeps with the white noise than not to sleep at all. Of course in the ideal world, our children would be able to magically fall asleep at will but you're one of the few if you have kids like that.

Answer 6

Read the book "The Brain that changes itself" by Norman Doidge. Work by Merzenich indicates that white noise during a critical period of brain development could be very damaging. The pertinent information begins around page 74.

Here is a summary provided by another website (Accuracy of the quotes not verified):

Infants are reared in continuously more noisy environments. There is always a din,” he says. White noise is everywhere now, coming from fans in our electronics, air conditioners, heaters and car engines. How would such noise affect the developing brain? Merzenich wondered.

To test this hypothesis, his group exposed rat pups to pulses of white noise throughout their critical period [of brain development during infancy] and found that the pups [brain] cortices were devastated.

“Every time you have a pulse,” Merzenich says, “you are exciting everything in the auditory cortex – every neuron.” So many neurons firing results in a massive BDNF [hormone] release. And as his model predicted, this exposure brings the critical period to a premature close. The animals are left with undifferentiated brain maps and utterly indiscriminate neurons that get turned on by any frequency.

Merzenich found that these rat pups, like autistic children, were predisposed to epilepsy, and exposing them to normal speech caused them to have epileptic fits… Merzenich now had his animal model for autism.

Recent brain scan studies now confirm that autistic children do indeed process sound in an abnormal way. Merzenich thinks that the undifferentiated cortex helps to explain why they have trouble learning, because a child with an undifferentiated cortex has a very difficult time paying attention. When asked to focus on one thing, these children experience booming, buzzing confusion – one reason autistic children often withdraw from the world and develop a shell. Merzenich thinks this same problem, in a milder form, may contribute to more common attention disorders.

The extract comes from “The Brain That Changes Itself” by Norman Doidge, 2010 revised edition, Scribe Publications Pty Ltd, pages 81-82.

Answer 7

I recommend you get a copy of Happiest Baby on the Block.

The short answer is no, white noise at that age will not damage your baby's hearing, it is in fact quieter than what they were used to while in the womb and VERY similar to what has been used to hearing 24/7 for the last several months. Which is why it works so well at soothing.

Congratulations, you have stumbled upon a VERY successful method of soothing your child.