Science Questions

How does an unborn baby hear?

Sun, 14th Oct 2012

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Joanne, from Lincolnshire asked:

How does an unborn baby hear because they definitely react to different sounds?


Chris -   Joanne is in Lincolnshire and she’s with us.  Hello, Joanne.

Joanne -   Hello.

Chris -   Your question…

Joanne -   How does an unborn baby hear because they definitely react to different sounds?

Chris -   Absolutely true, yes, they do and a lot of research has been done on this actually including a very nice study that was done by scientists in America about 10 years ago now.  They were interested in the amount of sound that pregnant women may experience in the military because with increasing numbers of women taking part in armed services work, they wanted to be sure that there wasn’t a potential danger to an unborn child, so they did experiments where they took a sheep that was pregnant and they put in a microphone inside the sheep’s uterus, in the ear of the developing lamb and they recorded sounds from there and also, outside the sheep.  And they made recordings of sounds played at the sheep with a loud speaker and then asked a group of volunteers to listen back to what they'd recorded.  And they found that about 1/3 to ˝ of the recordings were perfectly intelligible when the volunteers listen to them.  They could repeat back the words that have been played out of the speaker.  The reason for that is that sound waves, just as Owen was explaining a compression wave, they vibrate things and fluid conveys sound waves extremely efficiently.  And so, the vibrations will hit the side of the sheep or the human.  They then go through the muscles in the skin and they then hit the uterus, which is the womb and then make the fluid inside it vibrate and those vibrations can be carried to the ears of whatever is developing inside.  So, a baby is literally listening to its mum’s voice and other studies have shown that when babies pop out, they are born, tuned to their mother’s voice and they even imitate her accent regionally when they cry.  And this was proven a couple of years ago, comparing babies born to German and French mothers, and the cries had a very different pattern which was similar to the way that you speak those 2 different languages.  But a lovely question.  Thank you for joining us with it.

Joanne -   Thank you.


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