Misparsing coarticulation

Abstract

Considerable evidence shows that listeners often successfully compensate for coarticulation, and parse the speech signal's acoustic properties into their articulatory sources. Our experiments show pervasive misparsing of the acoustic effects of anticipatory coarticulation. Listeners categorized more of a front-back vowel continuum as back before [p] than [t]. A following [p] causes F2 and F3 to fall at the end of preceding vowels, and these listeners treated these falls as information that the vowel was back because F2 and F3 are also lower in back vowels. In experiment 1, misparsing was more extensive in a lax front-back continuum [ɛ-ْ] than in a tense one [e-o], but the lax vowels were also shorter. In experiment 2, the durations of lax and tense vowels were equalized, and the steady-state:transition ratios were varied from the naturally occurring 70:30 to 50:50 and 30:70. Listeners still misparsed consonantal formant transitions more for lax than tense vowels, likely because the acoustic differences between [ɛ] and [ْ] are smaller than those between [e] and [o]. They also misparsed more as transitions lengthened relative to the steady-state, which suggests that they did not adjust for differences in speaking rate that would affect the steady-state:transition ratios.