Mothers exaggerated acoustic-phonetic characteristics in infant-directed speech are highly correlated with infant’s speech discrimination skills in the first year of life

In addition to the well documented suprasegmental features of infant-directed speech, recent studies demonstrate that critical acoustic-phonetic features are exaggerated at the level of segments in infant-directed speech (IDS) Kuhl et al. (1997); Liu et al. (2000); Burnham et al. (2002). The speech directed to infants contains acoustically more extreme vowels when compared to adult-directed speech, resulting in an expanded vowel space. The relationship between the exaggerated characteristics of IDS and infants’ speech perception skills has not previously been examined. The present study tested the hypothesis that there is a correlation between characteristics of speech input and speech perception sensitivity for individual infants in the first year of life. Thirty-two Mandarin Chinese mothers’ speech samples were recorded in infant-directed and adult-directed speech conditions. The acoustic analysis demonstrated that Mandarin mothers modify their speech when speaking to their infants, amplifying the important acoustic cues. More importantly, the acoustic-phonetic characteristics in a particular mother’s infant-directed speech are significantly correlated with her infant’s speech perception. This result supports the view that hyperarticulation of the phonetic units in infant-directed speech facilitates infant’s language development. Work supported by NIH grant (HD37954) and Talaris Research Institute.