Il mito dell’isocronia moraica in giapponese. Un’analisi quantitativa basata su corpora orali

Pike (1945) classified the world languages into two types of rhythmic/prosodic patterns: stress-timed and syllable-timed. According to this classification, stress-timed languages, like English and German, tend to have isochronous interstress intervals, while syllable-timed languages, like Italian and Spanish, tend to have equal syllable duration. Ladefoged (1975) added the mora-timed type, in which isochrony is maintained at the level of the mora, a sub-syllabic constituent that includes either onset and nucleus, or a coda. Japanese is often referred to as a mora-timed language (Otake 2015): the mora is the psychological prosodic unit in spoken language, and the metric unit of traditional poetry (Bloch 1950). The syllabaries, in which each grapheme corresponds to a mora, make this prosodic segmentation clear. However, previous experimental studies have claimed that the mora is not a perfect isochronousunit (Warner and Arai 2001).The aim of this paper is to present the rhythm-prosodic system of the Japanese language giving a precise description of its prosodic units --the mora and the syllable--, and to provide empirical quantitative data on the duration of mora in spontaneous Japanese. The dataset used in the present study is a portion of the Corpus of Spontaneous Japanese called Core, consisting ofabout 45 hours ofextensively annotated speech. The variation of the average duration of the mora has been analysed on the basis of linguistic parameters, such as the typology of mora and the phonotactic structure of the word in which it is included, and of extra-linguistic parameters,such as the typology of speech.