Pssst! Baby listen! Communication is the key to survival when you are as helpless as babies and small children are. It has been known for decades that fetuses do not swim completely isolated in the amniotic fluid, but over time are able to receive not only the structure-borne noise of their mothers, but also information from the outside world. The hearing is ready for use from around the 24th to 28th week of pregnancy. However, what acoustically penetrates to the fetus is limited for purely physical reasons. The mother’s abdominal wall and the amniotic fluid only allow vibrations that are below a frequency of 600 Hertz (1 Hertz = one vibration per second) to pass through. All higher tones are greatly attenuated. The open frequency range is sufficient at least for the basic tones of the human voice: around 125 Hertz for adult men and 250 Hertz for women. Even children’s voices with a fundamental tone of around 440 Hertz are still clearly perceived in the womb.
But we don’t speak in the same tone. So-called overtones, i.e. a multitude of superimposed vibrations that result from the anatomy of our vocal tract, create the character and color of a tone sequence. However, this frequency range goes up to around 12,000 Hertz and remains hidden from unborn babies. Ideally, people can still hear sounds up to 20,000 Hertz, but significantly lower frequencies are realistic and pleasant for the ear. And of course the volume also plays a role: To be heard in the womb, it needs around 90 decibels (dB) outside, which corresponds roughly to the level in a fully occupied restaurant and, for example, in accordance with the DIN standard 18.005 “Sound insulation in urban development ” is significantly louder than loud street noise or a raging crowd of children endured up close.
What is primarily perceived by the baby in the womb is the rhythm and melody of a language. As previous research has shown, even newborns can distinguish speech from nonsense sounds. You also have an idea that there are such things as syllables and words, and where one word ends in an acoustic stream and another begins. However, this only works with the native language. Only with her does the newly born child discover the basic structures by analyzing characteristics such as rhythm, pitch and the intensity of what is said. Of course it doesn’t have to want to. The brain does this – like almost everything else – all by itself. But how does he know that the exact language he is now hearing is that of his mother and then usually of the entire family? When did the child learn this without understanding a word of the content of any language?
Access to all STERN PLUS content and articles from the print magazine
ad-free
Already registered?
