Acoustic Correlates of Word-Initial Obstruents of the Ikema Dialect of Miyako Ryukyuan

要旨

The Ryukyuan languages spoken in Ryukyu Islands of Japan are known to have typologically rare word-initial geminates.However, the phonetic aspects of Ryukyuan languages are still scarcely documented in the literature.The current study investigates the acoustic correlates of manner, place, voicing, and length in word-initial obstruents of endangered Ikema Miyako Ryukyuan, using a wide range of temporal and non-temporal measures (duration, FO, intensity, Fl, and F2).The results showed that duration is the most reliable acoustic correlate for the classification of manner, voicing, and length contrasts of word-initial obstruents.F1 contributed to the classification of manner and voicing whereas intensity additionally distinguished the length contrasts.The overall findings indicated that Ikema speakers can use a combination of temporal and non-temporal acoustic correlates to tease apart the subtle consonantal distinctions.The findings of the current study will help inform the phonetic and phonological typology of Ryukyuan languages and will further contribute to the studies of speech production in endangered languages. IntroductionThe Ryukyuan languages spoken in Ryukyu Islands of Japan share a common protolanguage with Japanese (Karimata 2015, Pellard 2015).The Ikema dialect of Miyako Ryukyuan language is mainly spoken on Ikema Island, in Sarahama on Irabu Island, and in Nishihara on main Miyako Island (Shinohara & Hussain 2020, Figure 1).! Ikema was originally spoken only on Ikema Island but during the 18th and 19th centuries, a part of the population migrated to neighboring islands.The estimated number of Ikema speakers in 2022 was around 1300 (Nakama et al. 2022).Ikema is no longer learned by the younger generation.As is the case with all the Ryukyuan languages, most of the speakers of Ikema are above 50 years of age (Nakayama & Ono 2013).Thus, the current status of Ikema as a severely endangered language calls for a detailed acoustic-phonetic study which will help inform phonetic and phonological typology.The current study will be a valuable addition to the ongoing discussions regarding the perception and production of a rare type of speech sounds in the world's languages (

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