Yanagawa Japanese is known to have voiced geminates (e.g., /omaeddoN/ omaeddoN “you”) while voiced geminates are marked and avoided in many languages, including standard Tokyo Japanese. Yanagawa Japanese exhibits not only phonological but also phonetic characteristics that are distinct from those of Tokyo Japanese (Shinohara et al. [J. Acoust. Soc. Am. 143, 1967–1968 (2018)). However, in recent years, many dialects of Japanese have undergone sound changes due to the influence of Tokyo Japanese, leading to a gradual loss of dialect-specific characteristics. Yanagawa Japanese is also likely to be undergoing such a shift. To examine this possibility, a production experiment was conducted in which 16 native speakers of Yanagawa Japanese (ranging from 27 to 90 in age) uttered six disyllabic words, consisting of three minimal pairs for voicing contrast (e.g., pappa versus pabba) with a carrier phrase. The results showed differences between the two groups: younger speakers exhibited significantly less vocal fold vibration during the closure interval of voiced geminates. These findings suggest that Yanagawa Japanese is undergoing sound change, with younger generations diverging from the traditional phonetic realization of voiced geminates.
Shoji Ishibashi (Wed,) studied this question.