Tones in Hakka Infant-Directed Speech: An Acoustic Perspective

This study explores lexical tones in Hakka infant-directed speech (IDS) in comparison with adult-directed speech (ADS), investigating whether lexical tones are hyperarticulated and distorted in Hakka IDS. Special attention is directed at the tonal contrast between unchecked and checked tones, an iss...

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Bibliographic Details
Published in:Language and linguistics (Taipei) 2014-04, Vol.15 (3), p.341-390
Main Authors: Cheng, Ming-chung, Chang, Kuo-chih
Format: Article
Language:English
Subjects:
Acoustics
Child-directed speech
Continuous speech
Cues
Fundamental frequency
Glottalization
Infants
Language acquisition
Learning
Linguistics
Parents & parenting
Phonetics
Speech duration
Spontaneous speech
Syllables
Tone
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Summary:This study explores lexical tones in Hakka infant-directed speech (IDS) in comparison with adult-directed speech (ADS), investigating whether lexical tones are hyperarticulated and distorted in Hakka IDS. Special attention is directed at the tonal contrast between unchecked and checked tones, an issue never investigated previously. Sixteen mother–infant dyads participated in this study, with infants’ age ranging from 6 to 26 months. The speech stimuli contained 18 disyllabic phrases in the form of C1V1C2V(C), where C1 and C2 are voiceless consonants and V1 (a corner vowel [i, a, u]) carried the target tone. Mothers interacted with their infants and the researcher naturally at their homes. Interviews were recorded as IDS and ADS. For each recording, the first two clear tokens of each target tone were segmented out for acoustic analysis of fundamental frequency (F0) by PRAAT. Results show that lexical tones in IDS are phonetically enhanced by exaggerated F0 contour, elevated F0 mean, widened F0 range, steepened F0 slope, lengthened F0 duration, and expanded tonal distance. Yet they are not distorted because they can still be distinguished by one or more F0 cues. All hyperarticulated cues contribute to perceptually salient linguistic signals, and help infants with tonal identification and categorical learning. More significantly, checked and unchecked tones have different tonal behaviors in ADS and IDS. Both tone types overlap in ADS, but separate in IDS. This tonal separability results from glottalization of the [p, t, k] codas in the production of checked-tone syllables in spontaneous and continuous speech.
ISSN:1606-822X
2309-5067
DOI:10.1177/1606822X14520662