Abstract
When addressing their young infants, parents systematically modify their speech. Such infant-directed speech (IDS) contains exaggerated vowel formants, which have been proposed to foster language development via articulation of more distinct speech sounds. Here, this assumption is rigorously tested using both acoustic and, for the first time, fine-grained articulatory measures. Mothers were recorded speaking to their infant and to another adult, and measures were taken of their acoustic vowel space, their tongue and lip movements and the length of their vocal tract. Results showed that infantbut not adult-directed speech contains acoustically exaggerated vowels, and these are not the product of adjustments to tongue or to lip movements. Rather, they are the product of a shortened vocal tract due to a raised larynx, which can be ascribed to speakers’ unconscious effort to appear smaller and more non-threatening to the young infant. This adjustment in IDS may be a vestige of early mother-infant interactions, which had as its primary purpose the transmission of non-aggressiveness and/or a primitive manifestation of prelinguistic vocal social convergence of the mother to her infant. With the advent of human language, this vestige then acquired a secondary purpose-facilitating language acquisition via the serendipitously exaggerated vowels.
Original language | English |
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Article number | 170306 |
Number of pages | 11 |
Journal | Royal Society Open Science |
Volume | 4 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2017 |
Open Access - Access Right Statement
© 2017 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.Keywords
- English language
- language acquisition
- parent and infant
- speech perception
- vowels