ACOUSTICAL FEATURES OF CHILDREN’S VOWEL SOUNDS: DEVELOPMENT BY CHRONOLOGICAL AGE VERSUS BONE AGE*

The acoustic development of four vowel sounds in children’s speech during the first six years was studied to determine whether statistically significant differences in formant frequency are apparent when chronological age is compared with a measure of physiological age. Thirty pre-school children were recorded in free verbalization situations. Representative productions of the four vowels /i/, /æl /α/, /u / were analysed with a sound spectrograph and measurements made of Formants 1 and 2. Results indicate that when the formant frequency measurements are compared as chronological age v. physiological age, no difference is found. It is concluded that grouping children by a measure of physiological maturity, rather than by chrono-logical age, does not change the final results when examining the development of formant frequencies. Recent research into language acquisition has been chiefly concerned with aspects of grammer and syntax (Smith and Miller, 1966). The rapid anatomical and physiological development of the child (Harrison et al. 1964) means that aspects of the language process other than grammar, would be worth-while investigating. Of particular interest are acoustical features of speech sounds children use, since it may be assumed that such features are relatively unstable until physiological maturity is achieved