The womb is arguably a noisy environment.
The baby can hear all sorts of noises that we don’t even notice normally. Their mom’s heartbeat, rumbling and gurgling sounds of her stomach, wheezing and whistling when she is breathing, or the blood flowing through the umbilical cord…!
But, how about the sound from the outside world, can they hear it equally well?
And what if I listen to loud music? Would I put my unborn baby’s hearing at risk?
Well, read on to find out about your baby hearing the effect the loud noise might have on them.
Is Loud Music Harmful to a Baby in the Womb?
Yes, loud music can be harmful to an unborn baby if you are exposed to it for a long time. Such as if you work a five-day week, 8-hour shift in the entertainment industry, or a factory, for example. However, if you want to listen to loud music, i.e. go to an odd gig, your baby’s hearing shouldn’t be affected. Although they may feel distressed because of the intense noise, even though, the volume of sound that reaches them is much reduced in the womb.
How & When Do Babies Start Hearing The Outside Noise?
So, babies can hear the very first sound around 4.5 months of pregnancy, which is 18 weeks. And this very comforting sound will come from their mom’s body.
It won’t be until 6 months of pregnancy, though, that the sounds from the outside world will reach their developing ears.
And you may be relieved to learn that your unborn baby doesn’t hear exactly as loud as we do. In fact, they will perceive only around 50% of the volume that reaches us.
In the womb, the wall “absorbs” some of the noise from outside, so the babies hear muffled sounds. And this happens because the amniotic fluid and a few other layers of the mom’s body isolate the baby from the source and also because their ears cannot amplify the sound just yet. This means that the noise generated outside (in the air) is significantly reduced when it travels through the amniotic fluid (the water).
(Which explains, by the way, why the sound from the outside is much quieter when we are underwater.)
So, when the sound travels from one medium to the other, i.e. from air to water – the speed, direction and wavelength change, as well. And this change in sound dynamics directly impacts how the sound is perceived in a different medium.
But How Loud Can Baby Actually Hear in The Womb?
A scientist from the University of Florida conducted a study on how much an unborn sheep can hear in the womb.
In this study, they assumed human babies should hear similarly to sheep and that the acoustics of human and sheep wombs are broadly the same.
It turned out that baby sheep could hear low-frequency noise and feel the vibration.
(A low-frequency noise sounds like when you turn up the bass on the stereo, you can hear a low and rumbly sound.)
And this sound the sheep could hear because sound travels well at low frequency, so no problem with reaching them in the womb.
However, high-frequency noise gets obscured by the abdominal wall and the amniotic fluid.
(A high-frequency noise sounds more high-pitch or like birds chirping.)
Furthermore, the most explicit sound baby hears and later recognises is their mother’s voice. This is because the mother’s voice resonates through her body and bones as it travels through the air to the uterus.
…Okay, going back to the subject…
The bottom line is there is no need to stress about damaging your baby’s sensitive ears until your third trimester of pregnancy.
Until then, they cannot hear a sound outside the womb.
Loud Noise Exposure During Pregnancy
Now, knowing how much your baby can hear at a different stage of pregnancy, we should talk about how sound, /especially loud sound, will affect their hearing.
So, what is generally regarded as a loud sound is above 70 decibels (dB). And exposure for a prolonged time for this noise can damage hearing.
Also, any noise above 120 dB can cause immediate harm to hear.
Now, let’s take a real-life example.
- Motorcyclists are exposed to the noise of 85 dB, so unless they wear some earplugs, they are at risk of hearing loss.
- City traffic, lawnmowers, leaf blowers, and other electric equipment generates A similar level of noise.
- Car horn, approaching train will emit a 100 dB sound.
- Power tools, sirens, and jet engines will also create an acceptable noise level.
The rule of thumb is the louder the noise, the more damage it can cause, which is quite a logical conclusion if you’d asked me.
What can your unborn baby hear and feel in the womb?
Noise Exposure Over a Prolonged Period
While noise above 85dB is harmful, it is the time impact of exposure to noise which can have severe consequences. Because exposure to loud sounds on an everyday basis can cause permanent hearing damage.
So, if you work in a noisy environment when pregnant, such as in manufacturing, aviation, emergency response, farming, etc. the effect on your pregnancy and unborn baby can be rather severe.
- A number of studies carried out on pregnant women exposed to occupational noise are at risk of preterm birth and low-weight birth.
- Other studies have documented that continuous noise exposure during pregnancy may cause noise-induced hearing loss in the baby.
Also, don’t think that if you wear high-quality ear protection, you are fine. Your earplugs won’t protect your baby.
Therefore, the official recommendation is pregnant women shouldn’t be exposed to noise above 115 dB.
What About Going To A Concert In My Third Trimester?
Well, if you fancy going to a concert (as in just once during your pregnancy, not as a weekly routine, that is…) it shouldn’t affect your baby’s hearing.
(Remember, only around half of the noise from the outside world reaches their developing ears in the womb).
Although, it wouldn’t hurt to keep away from the speakers and opt for a quieter corner instead… As we mentioned before, loud music produces a low-frequency sound that your baby will definitely hear.
Also, remember babies do react to the noise and sound they can hear. So, sudden, loud noise (such as music) may startle them and harm them by causing distress.
Final Few Lines
The bottom line and the answer to the question in this post title are:
If you are subject to a high level of industrial noise for a prolonged time, and not wearing ear protection–then you can harm your unborn baby.
Your baby can suffer from low birth weight, premature birth, or noise-induced hearing loss.
However, if you fancy listening to loud music – but for a short moment – this shouldn’t harm your baby’s hearing. But perhaps you could wear the headphones to spare your bump the unnecessary excitement…