A change occurs between the ages of 6 and 9 months that will gradually make the baby a specialist in its mother tongue. For instance, we got them to listen to the syllables ma and ti appearing either within a single word, as in math matique, or at the break between two words, as in panorama tib tain. Already at three days, the new-born infants were able to differentiate between these two prosodic signals. In particular, the stressed syllable changes position from word to word. This result reinforces the idea that the ability to process languages is a universal characteristic present at birth.
Arrows indicate the breaks between words.
The scientists confirmed that prosody is used constantly in the processing of unbroken speech, even unconsciously. Until then, our language ability, although already very specialized, stills retains some flexibility. Once adulthood is reached, however, the mother tongue becomes a noticeable filter, through which the pronunciation and prosody of any foreign language are deformed. There were two reasons for this. Firstly, the distinction between l and r is difficult for Japanese adults.