What Babies Hear Whilst Inside Their Mothers?

New research reveals how much babies can hear in utero...
25 January 2004


Ultrasound on pregnant lady


Researchers in America have discovered that the unborn baby can probably hear a lot more of what we say than we thought previously.

Ken Gerhardt and Robert Abrams, from the University of Florida, implanted a tiny microphone into the inner ear of a lamb developing inside its mother, and then played 64 recorded sentences on a loudspeaker near to the mother sheep. For comparison they also placed microphones in the uterus (womb) and in the open air next to the sheep.

Thirty human adults were asked to listen to the recordings from the various microphones and repeat what they heard. The volunteers understood all of the sentences recorded in the open air, about 70% of the sentences recorded in the womb and 30% of the sentences recorded in the fetal sheep's inner ear.

On the whole, the researchers found that low-frequency sounds were heard better than high frequency ones. Lead researcher Ken Gerhardt said [the intelligibility of sentences] was "actually much higher than we anticipated,". As for music, "they're not going to hear the violins, but they will hear the drums." 

This research is important because it has implications for babies born prematurely and placed in noisy baby units where there tend to be lots of high-pitched sounds which a baby of that developmental age would not normally be exposed to.


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