The Relationship between Laryngeal Constriction and Vowel Quality in Infants Learning English and Bai

This exploratory acoustic study focused on the relationship between laryngeal constriction and vowel quality in the vocalizations of infants aged 0-12 months learning Bai, which employs laryngeal constriction distinctively in its register tone system, and English, which uses laryngeal constriction only paralinguistically. Spectral tilt (H2-H1) measurements of front, neutral, and open vowels showed that for both groups, front vowels were least, and open vowels most, likely to be constricted, with neutral vowels falling in between. However, across vowel categories, Bai infants’ vowels were significantly more constricted than English infants’, suggesting the influence of the ambient language. Moreover, preliminary analysis of open vowels from months 1 through 12 suggests that English infants adopt a vocal setting that favours a lesser degree of constriction early in the first year of life, while Bai infants retain a vocal setting that results in a greater degree of constriction throughout the first year.