Editing Vowel length (section)

==Related features==
[[Stress (linguistics)|Stress]] is often reinforced by allophonic vowel length, especially when it is lexical. For example, [[French language|French]] long vowels are always in stressed syllables. [[Finnish language|Finnish]], a language with two phonemic lengths, indicates the stress by adding allophonic length, which gives four distinctive lengths and five physical lengths: short and long stressed vowels, short and long unstressed vowels, and a half-long vowel, which is a short vowel found in a syllable immediately preceded by a stressed short vowel: ''i-s'''o'''''.

Among the languages with distinctive vowel length, there are some in which it may occur only in stressed syllables, such as in [[Alemannic German]], [[Scottish Gaelic]] and [[Egyptian Arabic]]. In languages such as [[Czech language|Czech]], [[Finnish language|Finnish]], some Irish dialects and [[Classical Latin]], vowel length is distinctive also in unstressed syllables.

In some languages, vowel length is sometimes better analyzed as a sequence of two identical vowels. In [[Finnic languages]], such as Finnish, the simplest example follows from [[consonant gradation]]: ''haka → haan''. In some cases, it is caused by a following [[chroneme]], which is etymologically a consonant: ''jää'' "ice" ← [[Proto-Uralic]] *''jäŋe''. In non-initial syllables, it is ambiguous if long vowels are vowel clusters; poems written in the [[Kalevala meter]] often syllabicate between the vowels, and an (etymologically original) intervocalic ''-h-'' is seen in that and some modern dialects (''taivaan'' vs. ''taivahan'' "of the sky"). Morphological treatment of [[diphthong]]s is essentially similar to long vowels. Some old Finnish long vowels have developed into diphthongs, but successive layers of borrowing have introduced the same long vowels again so the diphthong and the long vowel now again contrast (''nuotti'' "musical note" vs. ''nootti'' "diplomatic note").

In Japanese, most long vowels are the results of the phonetic change of [[diphthong]]s; ''au'' and ''ou'' became ''ō'', ''iu'' became ''yū'', ''eu'' became ''yō'', and now ''ei'' is becoming ''ē''. The change also occurred after the loss of intervocalic phoneme {{IPA|/h/}}. For example, modern ''Kyōto'' ([[Kyoto]]) has undergone a shift: {{IPA|/kjauto/ → /kjoːto/}}. Another example is ''shōnen'' (''boy''): {{IPA|/seuneɴ/ → /sjoːneɴ/ [ɕoːneɴ]}}.