Emergence of the corner vowels in the babble produced by infants exposed to Canadian English or Canadian French

This paper examined the emergence of corner vowels ([i], [u], [æ] and [a]) in the infant vowel spaces and the influence of the ambient language on babbling, in particular, on the frequency of occurrence of the corner vowels. Speech samples were recorded from 51 Canadian infants from 8 to 18 months of age, respectively, English-learning infants (n=24) and French-learning infants (n=27). The acoustic parameters (F1 and F2) of each codable infant vowel were analyzed and then used to plot all the vowels along the diffuse-compact (F2-F1) and grave-acute dimensions ([F1+F2]/2). Listener judgments of vowel category were obtained for the most extreme vowels in each infant's vowel space, i.e., the 10% vowels with minimum or maximum diffuse-compact and grave-acute values. The judgments of adult listeners, both anglophone (n=5) and francophone (n=5), confirmed the peripheral expansion of infant vowel space toward the diffuse and grave corners with age. Furthermore, English-learning infants were judged by both English and French-speaking listeners to produce a greater frequency of [u] in the grave corner, in comparison with French-learning infants. The higher proportion of [u] in English sample was observed throughout the age range suggesting the influence of ambient language at a young age.