Durational characteristics of Tokyo and Osaka varieties of Japanese

Japanese is often characterized as a moraic language, but how this manifests in speech rhythm and the temporal organization of segments is not yet fully understood. Moreover, studies investigating the extent to which these patterns differ across regional varieties have been limited, and the speech characteristics of Kyōtsū-go ("common language") as spoken by native speakers of dialects remain understudied. This study examines the temporal organization of speech in the Osaka dialect and in Kyōtsū-go spoken by native speakers of the Osaka and Tokyo dialects. We conducted an online speech production experiment using nonce words embedded in carrier phrases and measured the duration of segments across different syllable types: light syllables (e.g., pata), and heavy syllables with long vowels (paata), geminates (patta), and moraic nasals (panta). The results suggest that even the so-called “mora dialects” exhibit variation in the temporal organization of segments within prosodic units at the phonetic level, with Kyōtsū-go spoken by native speakers of the Osaka dialect showing intermediate durational tendencies. These findings highlight the possibility that dialects characterized as moraic do not necessarily share the same durational patterns, and that speakers may vary their temporal characteristics depending on the linguistic or social context.