Developmental changes of vowel spectral properties for Mandarin-speaking children

To study the developmental changes in spectral properties of the Chinese vowels for Mandarin-speaking children, 270 children ranging from 6 to 16 years of age are studied. The result shows that: (1) The formant values for the vowels of children gradually decrease with increases in age. (2) The age-related developmental change in vowel formant frequencies is inconsistent across different vowel categories. (3) The vowel triangles area for the Mandarin-speaking children of both genders in F1-F2 plane gradually reduce to converge to the corresponding those for the Mandarin-speaking adults of both genders. (4) The ratios of F2 to F1 and F3 to F2 for the vowels can be used as the unchanged acoustic features to represent the similarities in the developmental changes of the vowels with increases in age across gender.