Phonotactics
In the same way that English words are divided into syllables, Japanese words are divided into moras (as the katakana and hiragana phonetic writing systems explicitly do), which are referred to in Japanese as "on" (or "onji"). Each mora has the same approximate time value and stress (stress, here, being correlated with pitch, not loudness). The Japanese mora may consist of either a vowel or one of the two moraic consonants, /N/ and /Q/. A vowel may be preceded by an optional (non-moraic) consonant, with or without a palatal glide /j/. In this table, the period represents a division between moras, rather than the more common usage of a division between syllables.
| Mora Type | Example | Japanese | moras per word |
| V | /o/ | o 尾 'tail' | 1-mora word |
| jV | /jo/ | yo 世 'world' | 1-mora word |
| CV | /ko/ | ko 子 'child' | 1-mora word |
| CjV | /kjo/1 | kyo 巨 'hugeness' | 1-mora word |
| N | /N/ in /ko.N/ or /ko.n/ | kon 紺 'deep blue' | 2-mora word |
| Q | /Q/ in /ko.Q.ko/ or /ko.k.ːo/ | kokko 国庫 'national treasury' | 3-mora word |
- ^1 Traditionally, moras were divided into plain and palatal sets, the latter of which entailing palatalization of the consonant element.
Consonantal moras are restricted from occurring word initially, though utterances starting with are possible. Vowels may be long, and consonants may be geminate (doubled). Geminate consonants are limited to /ɴn/, /ɴm/ and sequences of /Q/ followed by a voiceless obstruent, though some words are written with geminate voiced obstruents. In the analysis without archiphonemes, geminate clusters are simply two identical consonants, one after the other.
In English, stressed syllables in a word are pronounced louder, longer, and with higher pitch, while unstressed syllables are relatively shorter in duration. In Japanese, all moras are pronounced with equal length and loudness. Japanese is therefore said to be a mora-timed language.
Read more about this topic: Japanese Phonology