ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4pSC3. Identification of natural and synthesized vowels produced by children and adults: Effects of formant frequency variation.

Peter F. Assmann

William F. Katz

Kathleen M. Jenouri

Phillip W. Hamilton

School of Human Development, Univ. of Texas at Dallas, Box 830688, Richardson, TX 75083-0688

To examine developmental patterns in the production and perception of American English vowels, recordings were made of 12 /hVd/ words from 10 men, 10 women, and 30 children (ages 3, 5, 7). Fundamental frequency (F0) and formant center frequencies (F1--F4) were estimated and a subset of the measurements served as input to a cascade formant synthesizer. Natural and synthesized vowels were presented to adult listeners for identification. Overall, natural tokens were identified more accurately than synthesized versions. Performance was significantly lower when time-varying changes in either F1 or F2 were replaced by constant values drawn from the vowel nucleus. A further drop in accuracy resulted when all formants (F1-F4) and F0 were ``flattened,'' consistent with findings of Hillenbrand [J. Acoust. Soc. Am. 97, 3245(A) (1995)]. These findings highlight the perceptual importance of time-varying changes in vowel spectra. It has been suggested that time-varying changes in the formants can improve the intelligibility of vowels whose spectral envelopes are sparsely sampled by harmonics of the source spectrum. Although the vowels produced by children were generally less well identified, there was no evidence of an increased contribution of formant frequency dynamics with decreasing age. [Work supported by Texas Advanced Research Program.]