September 22-25, 1997
Magnitude and variability of duration, pitch and formant frequencies are computed for speech collected from five to eighteen year-old children. The study confirmed that reduction in magnitude and variability are the primary indicators of speech development. Specifically, children below age ten exhibit wider dynamic range of vowel duration, longer suprasegmental duration, and larger temporal and spectral variations. These trends diminish around age twelve. Children's speech acoustic characteristics fully develop to adult level in both magnitude and variability around age fifteen. Change of formant frequencies in male speakers parallels the growth of the vocal tract, while for female speakers the presence of such a linear trend is not clear. We conclude that the primary factors governing the acoustic patterns during speech development are anatomical maturation of the speech apparatus and speech motor control in terms of agility and precision.
Bibliographic reference. Lee, Sungbok / Potamianos, Alexandros / Narayanan, Shrikanth (1997): "Analysis of children's speech: duration, pitch and formants", In EUROSPEECH-1997, 473-476.