What Can My Baby Really Hear In The Womb?

Most people know that as your baby grows and develops outside sounds will become audible to him or her. Around week 25 or 26, babies in-utero have been shown to actually RESPOND to voices and noise.  Loud noises can even change your baby’s heart rate and movements, and sometimes even cause them to empty their bladders!  These noises will be muffled; but what about the noise they hear inside the womb?  Exactly how loud is it and are sound machines meant to mimic the comforting + familiar noises your newborn is used to?

A study published by NCBI placed an electrically isolated microphone inside the uterus of nine term volunteers.  They found that baseline intrauterine sounds were at 72-88db.  That’s similar to the sound of a lawn-mower!  Their conclusion was that the term fetus is exposed to physiologic sound levels much higher than we anticipated.

However we can’t stop there; there is one large factor to sound that we don’t experience in the “outside world”- and that’s the effect of amniotic fluid. Since the amniotic fluid fills the inner ear, it prevents the eardrum from amplifying sounds in the way it will once baby is born; and it also dampens high-pitched noises.  Some studies showed that the amniotic fluid created an automatic sound drop of 15-20db. However, the amniotic fluid actually amplifies low-pitched sound slightly.

The best example I can think of to describe this phenomena of low-pitched vs high-pitched noise is the sound we hear while swimming underwater.  You know how your mom would yell, “It’s time to leave!” and you’d keep dunking yourself so that you “couldn’t hear her”??  But when Dad steps in with the no-mess voice (a lower pitched sound) you are out of that pool in 2 seconds flat!  The noise was likely amplified, and you knew your parents meant business.

Basically for reference; if we take into the account of the amniotic fluid we can estimate that baby’s environment in the womb at any given time is anywhere from the noise level of an air conditioner to about a garbage disposal!  Pretty loud right?!  So that brings me to the next part- white noise! Should we use it?  How loud should it be?  When should I use it?

White noise can be a GREAT tool for calming a fussy baby; in fact it’s widely known as one of the best baby sleep tools!  It can act as a terrific cue for sleep if used for naps and bedtime.  However it’s important to note that if you’re using white noise for naps and bedtime- DO NOT use an automatic shut off setting as it could disrupt the sleep cycle.

S how loud should we play white noise? If the white noise is bothering your ears, it’s definitely going to be bothering your infants’ ears. It’s safe to assume that the loudest setting it TOO loud. Remember- your baby no longer has the amniotic fluid “cushion” and infant’s aren’t able to differentiate noise like adults.   The current recommendation for safe white noise levels is 50db;  that’s roughly the sound of someone taking a shower.


  1. White noise blocks out stimulation– therefore decreasing the stress that infant’s can feel with all the new and exciting things they are taking in.  They need a break too!
  2. White noise helps baby cry less.  Have you ever noticed that when a baby is crying nearly anyone around them will start sweetly shushing?  Shushing is a universal sound we all use to calm babies- it’s basically a white noise sound we make ourselves!  The trick is to shush or use white noise that is louder than the crying- so they can actually hear the “shush” or the white noise over the sound of their own cries.  This is where a white noise machine comes in suuuuper handy!  It can feel slightly ridiculous to shush louder than an infant’s cries for a period longer than a few minutes!
  3. White noise helps baby sleep.  The repetitive noise can help baby reset their sleep cycle so that they sleep longer than 20-45 minute stretches at a time.  It also blocks out outside sounds, like older siblings or the garbage truck!
  4. White noise can reduce the risk of SIDS.  White noise reduces active sleep, which is the sleep that SIDS is most likely to occur in. There have also been studies that have shown that the use of a fan can reduce the risk of SIDS- the reason is unknown whether its the cycling of air or the noise the fan makes.

So let’s talk about the BEST white noise machines (at all price points) to finish it off!  I’ll keep this part short and sweet.

This sound machine is portable which is super convenient for nap-time on the go, and ease when traveling.  Love that you can hook it onto a car seat or stroller!  I also love that it features a lock so that tiny hands can’t turn it off- baby and mischievous siblings included ;).

This sound machine is made by the same company as the portable machine above + had one of the highest ratings on Amazon + was the most recommended to me from my call for “best sound machines” on instagram.  What’s unique about this machine is it has a fan inside so the sound is natural instead of computerized.  A friend of mine told me her brother in law has major sleep issues and he swears by this for a good night’s sleep!

Another recommended product through one of my followers- if you want to kill two birds with one stone consider an air purifier.  Something you will likely want to consider if you have pets! It’s a pricier buy; but like I said- two birds! This one is the #1 recommended and reviewed on Amazon.

Next we have “The Baby Shusher”.  This product mimics the natural “shushing” noise, which is the technique used in the book, “The Happiest Baby On The Block”.  After talking to a few users I learned that it’s best for the newborn stage, but you’ll want something more traditional if you continue using a white noise machine throughout baby’s first year + beyond.

Last but not least I wanted to include a couple super affordable options.  I can’t guarantee the durability of these products but you can’t beat the price!


And here is a super affordable, portable option.  Can’t beat $9.99!

What do you think?  Will you be using a white noise machine with your baby?  What white noise machines have you used and loved??


*photo credit: @kennedydenephotos + @demilucymay