Australian English listeners' perception of Japanese vowel length reveals underlying phonological knowledge.

Speech perception patterns are strongly influenced by one's native phonology. It is generally accepted that native English listeners rely primarily on spectral cues when perceiving vowels, making limited use of duration cues because English lacks phonemic vowel length. However, the literature on vowel perception by English listeners shows a marked bias toward American English, with the phonological diversity among different varieties of English largely overlooked. The current study investigates the perception of Japanese vowel length contrasts by native listeners of Australian English, which is reported to use length to distinguish vowels unlike most other varieties of English. Twenty monolingual Australian English listeners participated in a forced-choice experiment, where they categorized Japanese long and short vowels as most similar to their native vowel categories. The results showed a general tendency for Japanese long and short vowels (e.g., /ii, i/) to be categorized as Australian English long and short vowels (e.g., /i:, ɪ/ as in "heed," "hid"), respectively, which contrasts with American English listeners' categorization of all Japanese vowels as tense regardless of length (e.g., /ii, i/ as both "heed") as reported previously. Moreover, this duration-based categorization was found not only for Australian English categories that contrast in duration alone (e.g., /ɐ:, ɐ/ as in "hard," "hud") but also for those that contrast in both duration and spectra (e.g., /o:, ɔ/ as in "hoard," "hod"), despite their spectral mismatch from the corresponding Japanese vowels (e.g., /aa, a/ and /oo, o/). The results, therefore, suggest that duration cues play a prominent role across all vowel categories-even nonnative-for Australian English listeners. The finding supports a feature-based framework of speech perception, where phonological features like length are shared across multiple categories, rather than the segment-based framework that is currently dominant, which regards acoustic cues like duration as being tied to a specific native segmental category. Implications for second and foreign language learning are discussed.

Multiple Sources of Surprisal Affect Illusory Vowel Epenthesis.

Illusory epenthesis is a phenomenon in which listeners report hearing a vowel between a phonotactically illegal consonant cluster, even in the complete absence of vocalic cues. The present study uses Japanese as a test case and investigates the respective roles of three mechanisms that have been claimed to drive the choice of epenthetic vowel-phonetic minimality, phonotactic predictability, and phonological alternations-and propose that they share the same rational goal of searching for the vowel that minimally alters the original speech signal. Additionally, crucial assumptions regarding phonological knowledge held by previous studies are tested in a series of corpus analyses using the Corpus of Spontaneous Japanese. Results show that all three mechanisms can only partially account for epenthesis patterns observed in language users, and the study concludes by discussing possible ways in which the mechanisms might be integrated.

Recoverability-driven coarticulation: Acoustic evidence from Japanese high vowel devoicing.

High vowel devoicing in Japanese, where /i, u/ in a C1VC2 sequence devoice when both C1 and C2 are voiceless, has been studied extensively, but factors that contribute to the devoiced vowels' likelihood of complete deletion is still debated. This study examines the effects of phonotactic predictability on the deletion of devoiced vowels. Native Tokyo Japanese speakers (N = 22) were recorded in a sound-attenuated booth reading sentences containing lexical stimuli. C1 of the stimuli were /k, ʃ/, after which either high vowel can occur, and /ʧ, ϕ, s, ç/, after which only one of the two occurs. C2 was always a stop. C1 duration and center of gravity (COG), the amplitude weighted mean of frequencies present in a signal, were measured. Duration results show that devoicing lengthens only non-fricatives, while it has either no effect or a shortening effect on fricatives. COG results show that coarticulatory effects of devoiced vowels are evident in /k, ʃ/ but not in /ʧ, ϕ, s, ç/. Devoiced high vowels, therefore, seem to be more likely to delete when the vowel is phonotactically predictable than when it is unpredictable.