The interaction between predictability and pre-boundary lengthening on syllable duration in Taiwan Southern Min

This study investigated how predictability and prosodic phrasing interact in accounting for the variability of syllable duration in Taiwan Southern Min. Speech data were extracted from 8 hours of spontaneous speech. Three predictability measurements were examined: bigram surprisal, bigram informativity, and lexical frequency. Results showed that higher informativity and surprisal led to longer syllables. As for the interaction with prosodic positions, there was a general weakening of predictability effects for syllables closer to the boundary, especially in the pre-boundary position, where pre-boundary lengthening was the strongest. However, the effect of word informativity appeared to be least modulated by this effect of boundary marking. These findings are consistent with a hypothesis that prosodic structure modulates the predictability effects on phonetic variability. The robustness of informativity in predicting syllable duration also suggests a possibility of stored phonetic variants associated with a word's usual contextual predictability.