SPECTRAL DISCONTINUITIES AND THE VOWEL LENGTH EFFECT

Perception of voicing for stop consonants in consonant-vowel syllables can be affected by the duration of the following vowel so that longer vowels lead to more ''voiced'' responses. On the basis of several exp eriments, Green, Stevens, and Kuhl (1994) concluded that continuity of fundamental frequency (f0), but not continuity of formant structure, determined the effective length of the following vowel. In an extensio n of those efforts, we found here that both effects were critically de pendent on particular f0s and formant values. First, discontinuity in f0 does not necessarily preclude the vowel length effect because the e ffect maintains when f0 changes from 200 to 100 Hz, and 200-Hz partial s extend continuously through test syllables. Second, spectral discont inuity does preclude the vowel length effect when formant changes resu lt in a spectral peak shifting to another harmonic. The results indica te that the effectiveness of stimulus changes for sustaining or dimini shing the vowel length effect depends critically on particulars of spe ctral composition.