Effects of Surprisal and Entropy on Vowel Duration in Japanese

Abstract

Research on English and other languages has shown that syllables and words that contain more information tend to be produced with longer duration. This research is evolving into a general thesis that speakers articulate linguistic units with more information more robustly. While this hypothesis seems plausible from the perspective of communicative efficiency, previous support for it has come mainly from English and some other Indo-European languages. Moreover, most previous studies focus on global effects, such as the interaction of word duration and sentential/semantic predictability. The current study is focused at the level of phonotactics, exploring the effects of local predictability on vowel duration in Japanese, using the Corpus of Spontaneous Japanese. To examine gradient consonant-vowel phonotactics within a consonant-vowel-mora, consonant-conditioned Surprisal and Shannon Entropy were calculated, and their effects on vowel duration were examined, together with other linguistic factors that are known from previous research to affect vowel duration. Results show significant effects of both Surprisal and Entropy, as well as notable interactions with vowel length and vowel quality. The effect of Entropy is stronger on peripheral vowels than on central vowels. Surprisal has a stronger positive effect on short vowels than on long vowels. We interpret the main patterns and the interactions by conceptualizing Surprisal as an index of motor fluency and Entropy as an index of competition in vowel selection.

Contextual predictability influences word and morpheme duration in a morphologically complex language (Kaqchikel Mayan)

“…While the probabilistic reduction effect on word and morpheme duration has, to our knowledge, never been examined in an agglutinative language, there is nonetheless reason to suspect that such an effect could be found in Kaqchikel. Shaw and Kawahara (2017) examined the effect of local phonotactic predictability on vowel duration in Japanese, an agglutinative language. Two measures of conditional probability (surprisal and entropy) were found to independently influence vowel duration in this study.…”

Linguistic Laws in Speech: The Case of Catalan and Spanish

“… Lognormality law. Previous studies have found consistently lognormal distributions for spoken phonemes in several languages [ 25 , 26 , 27 , 28 , 36 ] and in word and breath groups (BGs) duration for English [ 4 , 37 ]. In [ 4 ] it was confirmed that the time duration of phonemes, words and breath groups in speech are well described by lognormal distribution for the English language.…”

Resilience of English vowel perception across regional accent variation

“…There are also converging results from the phonology literature, where there is a growing awareness that phonological categories are more graded in both production and perception than have been typically assumed (Hall, 2009;Smolensky, Goldrick, & Mathis, 2014;Warner, Jongman, Sereno, & Kemps, 2004). Factors affecting the strength of perceptual assimilation (i.e., tolerance of variance) may include the predictability of the vowel in context (Shaw & Kawahara, 2017), functional load (e.g., Hockett, 1967), phonological neighborhood density (Munson & Solomon, 2004), or phonetic salience (Carlson, Granstöm, & Klatt, 1979;Escudero & Vasiliev, 2011;Rosner & Pickering, 1994), factors that we plan to pursue in future studies.…”