Developmental changes in the acoustic vowel space of Mandarin-learning children before 2 years of age

Abstract

Vocalic productions of Mandarin-learning infants aged 0–24 months were audiotaped and analyzed. Major findings in this longitudinal study are (1) There is no obvious change in the range of F1 and F2 values during these 2 years; (2) Midcentral vowels occurs most frequently for infants younger than 6 months. Vowel /a/occurs most frequently in infants 7 to 24 months old; (3) The frequently occurring vowel categories show steadier pattern of vowel formant frequencies in the second year; (4) Other vowels develop rapidly from 18 months on. However, the newly developed /i, u/ are difficult to identify because of the low amplitude and short duration at this stage of development; (5) Diphthongs, triphthongs, and vowels with nasal endings appear. However, they are unstable, weak, abrupt, and incomplete in the transition. These cause great difficulty in perceptual judgment and acoustic analysis. (6) The individual differences found in the first year became less obvious in the second year. [Investigation supported through funds from National Science Council in Taiwan, Republic of China (NSC 90-2411-H-006-015) (NSC 92-2411-H-006-021) (NSC 93-2411-H-006-024) and a faculty grant from National Cheng Kung University.]