Japanese is a mora-counting language. In theory, each mora takes about ``the same length of time to say'', the so-called a mora-isochronism. A mora consists of V, CV, N, q (V : vowel, C : consonant, N : moraic nasal, q : moraic obstruent), respectively. The length of an utterance phonologically depends on the number of mora. For example, kaN (a can) and kana (syllabary) are two mora words which linguistically have the same duration[37]. However, the mora-isochronism still remains unsolved as a hypothesis. In addition, Japanese has the peculiar speech rhythm called Tokushuhaku that fundamentally does not follow the mora-isochronism : e.g., long vowels, moraic obstruent, and moraic nasal.
