Developmental change of vowel production in Cantonese children

The paper investigates the developmental change in formant frequencies (F1F2) of the vowels [i u ɛ ɔ a] in Cantonese male and female children of the ages ranging from 4 to 12. Results show that (i) a decrease in formant frequencies and vowel loop area is a function of age and the change is a gradual process; (ii) the developmental change with age is non-uniform across vowel types and formants, with a larger decrease in F1 for the mid and low vowels [ɛ ɔ a] than the high vowels [i u] and a smaller decrease in F2 for the rounded back vowels [u ɔ] than the unrounded front equivalents [i ɛ] and the low vowel [a]; (iii) the difference in vowel formant frequencies between male and female children starts at 7 years of age and peaks at 12 years of age; and (iv) the difference in vowel loop area between male and female children as a function of age is not significant.