Japanese phonology is the system of sounds used in the pronunciation of the Japanese language. Unless otherwise noted, this article describes the standard variety of Japanese based on the Tokyo dialect.
There is no overall consensus on the number of contrastive sounds (phonemes), but common approaches recognize at least 12 distinct consonants (as many as 21 in some analyses) and 5 distinct vowels, /a, e, i, o, u/. Phonetic length is contrastive for both vowels and consonants, and the total length of Japanese words can be measured in a unit of timing called the mora (from Latin mora "delay"). Only limited types of consonant clusters are permitted. There is a pitch accent system where the position or absence of a pitch drop may determine the meaning of a word: /haꜜsiɡa/ (箸が, 'chopsticks'), /hasiꜜɡa/ (橋が, 'bridge'), /hasiɡa/ (端が, 'edge').
Japanese phonology has been affected by the presence of several layers of vocabulary in the language: in addition to native Japanese vocabulary, Japanese has a large amount of Chinese-based vocabulary (used especially to form technical and learned words, playing a similar role to Latin-based vocabulary in English) and loanwords from other languages.[1] Different layers of vocabulary allow different possible sound sequences (phonotactics).