Age-related changes in acoustic modifications of Mandarin maternal speech to preverbal infants and five-year-old children: a longitudinal study

Acoustic-phonetic exaggeration of infant-directed speech (IDS) is well documented, but few studies address whether these features are modified with a child's age. Mandarin-speaking mothers were recorded while addressing an adult and their child at two ages (0;7-1;0 and 5;0) to examine the acoustic-phonetic differences between IDS and child-directed speech (CDS). CDS exhibits an exaggeration pattern resembling that of IDS-expanded vowel space, longer vowels, higher pitch and greater lexical tone differences - when compared to ADS. Longitudinal analysis demonstrated that the extent Of acoustic exaggeration Is significantly smaller in CDS than in IDS. Age-related changes in maternal speech provide Some Support for the hypothesis that mothers adjust their speech directed toward children as a function of the child's language ability.