Development of vowel quality and quantity throughout the first year

0534224 - PSÚ 2021 RIV DE eng A - Abstract
Chládková, Kateřina - Paillereau, Nikola - Smolík, Filip - Podlipský, V.J.
Development of vowel quality and quantity throughout the first year.
2019.
[Workshop on Infant Language Development (WILD). 13.06.2019-15.06.2019, Potsdam]
R&D Projects: GA ČR(CZ) GA18-01799S
Institutional support: RVO:68081740
Keywords : early discrimination of vowel contrasts * vowel quality and quantity * Czech
OECD category: Psychology (including human - machine relations)
https://www.uni-potsdam.de/wild2019/programme.html

Before their first birthday infants form categories for most native-language speech sounds with vowels being, most likely, acquired earlier than consonants, namely at about 6 months of age (Kuhl et al. 2004, Tsuji & Cristia 2014). Within the class of vowels, however, there are various types of contrasts that vary in their perceptual saliency which could affect the order in which they come to be acquired. While in all languages, vowels are contrasted by their spectral properties (Maddieson 1984), in some (e.g. Japanese, Finnish, Czech) vowel duration, too, cues phonological categories such that a short and a long vowel of the same spectral quality represent two different phonemes. Some have proposed that vowel duration in speech sounds is a more perceptually salient cue than spectrum (Bohn 1995), which could cause duration-cued contrasts to be acquired before spectral ones. Since language acquisition begins already in utero and fetuses are able to hear speech sound differences [Moon et al 1993, Gervain 2005), one could also reason that they could more easily learn from the durational than from spectral information as the latter undergoes significant attenuation when passing from the outside environment to the fetal ear (Granier-Deferre 2011). A review of previous studies with children acquiring vowel length does not provide unanimous evidence as to the order of vowel length vs vowel quality development (Mugitani et al. 2009, Sato et al. 2010). We thus tested the hypothesis that, thanks to their greater perceptual saliency in general – and more so in prenatal development – duration-cued contrasts are acquired before spectral ones. We traced the development of vowel length and vowel quality in infants acquiring Czech. Using the central fixation paradigm, 4-, 6-, 8-, and 10-month-olds (n = 16 per age) were habituated to tokens of a nonsense syllable /fɛ/ and subsequently presented with trials where /fɛ/ alternated with /fɛː/, /fa/, or /fɛ/ again. The difference in looking time to each type of change with respect to the average of the last two habituation trials was submitted to a linear-mixed effects model per age group, each containing Trial as a fixed effect with 2 orthogonal contrasts (spectral vs. no change, duration vs. no change). Participant was entered as a random factor, including random slopes per Trial type. A difference between durational and no change was detected in all four age groups. A difference between spectral and no change was detected in the 6-, 8-, and 10- month-olds. At 6 months the durational change yielded a stronger response (i.e. larger difference to no change) than the spectral change, no such Trial-type effects were observed for the two oldest groups. In summary, infants between 4 and 10 months perceptually discriminate vowel duration changes, and 4- and 6-month-olds discriminate duration more strongly than they discriminate vowel quality. This indicates that, in a language that employs contrastive vowel length, categories cued by duration might be acquired earlier than those cued by spectral quality. In order to rule out a potential alternative explanation in terms of large auditory saliency of duration as such, a follow-up experiment is underway that tests the discrimination of durational and spectral differences with non-speech stimuli.
Permanent Link: http://hdl.handle.net/11104/0312447