A Study On The Pitch Features Of Southern Infant-directed Speech In Mandarin Chinese

The present study explores the prosodic features of IDS (Infant-directed Speech) by comparing it with ADS (Adult-directed Speech) based on the data from a longitudinal study. The aims of the study are as follows: firstly, it aims to find whether Mandarin IDS does have the prosodic modifications which are reported from a variety of languages including both tonal and non-tonal languages. These prosodic modifications include higher mean F0 and exaggerated pitch range. And the main focus is the correlation between prosodic features and infants'age and gender. Secondly, the present study will investigate the prosodic features at the syllabic level. The pitch range, pitch contour and mean F0 of each tone will be examined in order to find whether the fundamental frequency of the four tones in IDS is modified and what kind of effects these modifications will bring to the tone identification.The subjects are six mother-infant dyads, and they are audio- and video- taped at their home weekly. There are equal numbers of male and female infants. The present study uses the recordings when the infants are 9 months, 12months, 15 months, 18 months, 21 months and 24 months old and the ADS samples are recorded between mothers and the experimenters when the infants are 18 months old. The software of Praat 5.1.01, SPSS 15.0 and Matlab are used to analyze the data. The measures of mean F0 and pitch range at both the sentential and syllabic levels are analyzed. Praat is used to get the pitch values for further analysis. Matlab is used to normalize the pitch values using Lz-score method. SPSS is used to compare the effects of each variable.The results show that Mandarin IDS does have the prosodic modifications of higher pitch and greater pitch range compared with ADS. When infants'age is taken into account, it is found that the measures of mean F0 and pitch range change across the age. Mean F0 increases from 9 months and gets its peak at 18 months, then decreases. The pitch range decreases as the infant grows old. When infants'gender is taken into account, speech addressed to male infants has a higher mean F0 but lower pitch range than that to female infants. The analysis of pitch measures at the syllabic level shows that IDS has higher mean F0 and expanded pitch range than ADS, but the contour shape of each tone is preserved and these prosodic changes don't impede tone identification. This result is consistent with Cao Jianfen's (2002) argument about the relationship between Mandarin tone and intonation. In IDS, when the mean F0 and pitch range are exaggerated at the sentential level, there also appear modifications of fundamental frequency at the syllabic level just like"small wave ride on big wave". And when the fundamental frequency is raised within a lexical tone, it's the register but not the contour shape changed.The conclusion can be drawn in view of these results. IDS has prosodic modifications that are different from ADS. The ambient language in which the infant is surrounded is not poor at all. IDS is rich in prosodic cues that can attract infants'attention, communicate affection and facilitate language development.