ACOUSTICS AND PERCEPTION OF DYNAMIC VOWEL SEGMENTS

Some 550 vowel segments have been excised from a text read by a Dutch speaker, both at normal rate and at fast rate. The duration of each segment is measured, as well as static and dynamic formant characteristics, such as midpoint formant frequencies, and descriptions of the formant tracks in terms of 16 equidistant points per segment, or Legendre polynomial functions. We examined these formant characteristics as a function of vowel duration, but found no indication for duration-dependent undershoot. Instead, this speaker showed very consistent consonant-specific coarticulatory behavior and adapted his speaking style to the speaking rate in order to reach the same midpoint formant frequencies. Various (parabolically stylized) formant tracks, at various durations, in isolation or in CVC contexts, were synthesized and presented to listeners for identification. Net shifts in vowel responses, compared to stationary stimuli, showed no indication of perceptual overshoot. A weighted averaging method with the greatest weight to formant frequencies in the final part of the vowel tokens, explained the results best.