An acoustic comparison of vowel systems in Adult direct speech and child directed speech

This research investigated the role of child-directed speech in the acquisition of vowel systems in a cross-linguistic perspective. In order to determine if vocalic systems are expanded in child-directed speech and if this extension varies cross-linguistically, child-directed speech (CDS) was compared to adult-directed speech (ADS) in three rhythmically different languages: French, English and Japanese. The same short story was successively read by mothers to their infant and to an adult (5 mother-infant dyads per language). In the three languages, mothers tended to produce more opened vowels in CDS than in ADS, resulting in a downward shift of the vowel space on the high-low dimension (F1)