Brief Research Report
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.
(Received September 02 2007)
(Revised March 24 2008)
(Online publication February 23 2009)
[*] This research was supported by a research grant from the National Science Council, Taiwan, to Huei-Mei Liu (NSC 92-2413-H-003-072 & NSC 93-2413-H-003-019). Patricia K. Kuhl's contribution was supported by the Hsin-Yi Foundation of Taiwan and an NSF Science of Learning Center grant (0354453).