Vowel length

In linguistics, vowel length is the perceived duration of a vowel sound. Often the chroneme, or the "longness", acts like a consonant, and may have arisen from one etymologically, such as in Australian English. While not distinctive in most other dialects of English, vowel length is an important phonemic factor in many of the world's languages and dialects, for instance in Arabic, Finnish, Fijian, Kannada, Japanese, Old English, Scottish Gaelic and Vietnamese. It plays a phonetic role in the majority of dialects of British English and is said to be phonemic in a few other dialects, such as Australian English, South African English and New Zealand English. It also plays a lesser phonetic role in Cantonese, unlike other varieties of Chinese.

Many languages do not distinguish vowel length phonemically. Those that do usually distinguish between short vowels and long vowels. A very few languages distinguish three phonemic vowel lengths, such as Luiseño and Mixe. However, some languages with two vowel lengths also have words in which long vowels appear adjacent to other short or long vowels of the same type: Japanese hōō "phoenix" or Ancient Greek ἀάατος "inviolable". Some languages that do not ordinarily have phonemic vowel length but permit vowel hiatus may similarly exhibit sequences of identical vowel phonemes that yield phonetically long vowels, such as Georgian გააადვილებ "you will facilitate it".

Related features
Stress is often reinforced by allophonic vowel length, especially when it is lexical. For example, French long vowels are always in stressed syllables. 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-so.

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, 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 diphthongs 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 diphthongs; 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. For example, modern Kyōto (Kyoto) has undergone a shift:. Another example is shōnen (boy):.

Phonemic vowel length
Many languages make a phonemic distinction between long and short vowels: Arabic, Sanskrit, Japanese, Biblical Hebrew, Scottish Gaelic, Finnish, Hungarian, etc.

Long vowels may or may not be analyzed as separate phonemes. In Latin and Hungarian, long vowels are analyzed as separate phonemes from short vowels, which doubles the number of vowel phonemes.

Vowel length contrasts with more than two phonemic levels are rare, and several hypothesized cases of three-level vowel length can be analysed without postulating this typologically unusual configuration. Estonian has three distinctive lengths, but the third is suprasegmental, as it has developed from the allophonic variation caused by now-deleted grammatical markers. For example, half-long 'aa' in saada comes from the agglutination *saata+ka "send+(imperative)", and the overlong 'aa' in saada comes from *saa+ta "get+(infinitive)". As for languages that have three lengths, independent of vowel quality or syllable structure, these include Dinka, Mixe, Yavapai and Wichita. An example from Mixe is "guava",  "spider",  "knot". In Dinka the longest vowels are three moras long, and so are best analyzed as overlong etc.

Four-way distinctions have been claimed, but these are actually long-short distinctions on adjacent syllables. For example, in kiKamba, there is, , , "hit", "dry", "bite", "we have chosen for everyone and are still choosing".

In English
The vowels of Received Pronunciation are commonly divided into short and long phonemes. The short vowels are (as in kit),  (as in foot),  (as in dress),  (as in strut),  (as in trap),  (as in lot), and  (as in the first syllable of ago and in the second of sofa). The long vowels are (as in fleece),  (as in goose),  (as in nurse),  as in north and thought, and   (as in father and start). While a different degree of length is present, there are also differences in the quality (lax vs tense) of these vowels. In General American, only tenseness is usually distinguished and vowels are transcribed without the length mark.

Allophonic vowel length
In most varieties of English, for instance Received Pronunciation and General American, there is allophonic variation in vowel length: vowels are shortened before fortis consonants but have full length in all other contexts (i.e. word-finally, before lenis consonants, nasals and ). The process is known as pre-fortis clipping. Thus the vowel in bad is of normal length but the vowel in bat  is shortened. Also compare neat with need. The clipping effect can result in phonologically long vowels becoming shorter than phonologically short vowels when they occur in pre-fortis position.

Contrastive vowel length
In Australian English, there is contrastive vowel length in closed syllables between long and short and sometimes. The following can be minimal pairs of length for many speakers:

"Long" and "short" vowels in orthography
In English spelling, vowel letters in words of the form CVC and CVCe (consonant + vowel + consonant + the letter e) are traditionally called "short" and "long" (and actually represent single vowels or diphthongs [combinations of two vowels]). A vowel letter is called "long" if it's pronounced the same as the letter's name and "short" otherwise. This is commonly used for educational purposes when teaching children how to read, but this system does not cover all vowels of English and the terminology is not linguistic. In phonetic transcription, "long" vowels may be marked with a macron; for example, /ā/ may be used to transcribe IPA /eɪ/. This is sometimes used in dictionaries, most notably in Merriam-Webster (see Pronunciation respelling for English for more).

The phonetic values of "long" and "short" vowels are represented in the table below:

Origin
Vowel length may often be traced to assimilation. In Australian English, the second element of a diphthong  has assimilated to the preceding vowel, giving the pronunciation of bared as, creating a contrast with the short vowel in bed.

Another common source is the vocalization of a consonant such as the voiced velar fricative or voiced palatal fricative, e.g. Finnish illative case, or even an approximant, as the English 'r'. A historically-important example is the laryngeal theory, which states that long vowels in the Indo-European languages were formed from short vowels, followed by any one of the several "laryngeal" sounds of Proto-Indo-European (conventionally written h1, h2 and h3). When a laryngeal sound followed a vowel, it was later lost in most Indo-European languages, and the preceding vowel became long. However, Proto-Indo-European had long vowels of other origins as well, usually as the result of older sound changes, such as Szemerényi's law and Stang's law.

Vowel length may also have arisen as an allophonic quality of a single vowel phoneme, which may have then become split in two phonemes. For example, the Australian English phoneme was created by the incomplete application of a rule extending  before certain voiced consonants, a phenomenon known as the bad–lad split. An alternative pathway to the phonemicization of allophonic vowel length is the shift of a vowel of a formerly-different quality to become the short counterpart of a vowel pair. That too is exemplified by Australian English, whose contrast between (as in duck) and  (as in dark) was brought about by a lowering of the earlier.

Estonian, a Finnic language, has a rare phenomenon in which allophonic length variation has become phonemic after the deletion of the suffixes causing the allophony. Estonian had already inherited two vowel lengths from Proto-Finnic, but a third one was then introduced. For example, the Finnic imperative marker *-k caused the preceding vowels to be articulated shorter. After the deletion of the marker, the allophonic length became phonemic, as shown in the example above.

IPA
In the International Phonetic Alphabet the sign (not a colon, but two triangles facing each other in an hourglass shape; Unicode U+02D0) is used for both vowel and consonant length. This may be doubled for an extra-long sound, or the top half may be used to indicate that a sound is "half long". A breve is used to mark an extra-short vowel or consonant.

Estonian has a three-way phonemic contrast:
 * saada "to get" (overlong)
 * saada "send!" (long)
 * sada "hundred" (short)

Although not phonemic, a half-long distinction can also be illustrated in certain accents of English:
 * bead
 * beat
 * bid
 * bit

Diacritics

 * Macron (ā), used to indicate a long vowel in Maori, Hawaiian, Samoan, Latvian and many transcription schemes, including romanizations for Sanskrit and Arabic, the Hepburn romanization for Japanese, and Yale for Korean. While not part of their standard orthography, the macron is used as a teaching aid in modern Latin and Ancient Greek textbooks. Macron is also used in modern official Cyrillic orthographies of some minority languages (Mansi, Kildin Sami, Evenki).
 * Breves (ă) are used to mark short vowels in several linguistic transcription systems, as well as in Vietnamese and Alvarez-Hale's orthography for O'odham language.
 * Acute accent (á), used to indicate a long vowel in Czech, Slovak, Old Norse, Hungarian, Irish, traditional Scottish Gaelic (for long [oː] ó, [eː] é, as opposed to [ɛː] è, [ɔː] ò) and pre-20th-century transcriptions of Sanskrit, Arabic, etc.
 * Circumflex (â), used for example in Welsh. The circumflex is occasionally used as a surrogate for the macrons, particularly in Hawaiian and in the Kunrei-shiki romanization of Japanese, or in transcriptions of Old High German. In transcriptions of Middle High German, a system where inherited lengths are marked with the circumflex and new lengths with the macron is occasionally used.
 * Grave accent (à) is used in Scottish Gaelic, with a e i o u. (In traditional spelling, [ɛː] is è and [ɔː] ò as in gnè, pòcaid, Mòr (personal name), while [eː] is é and [oː] is ó, as in dé, mór.)
 * Ogonek (ą), used in Lithuanian to indicate long vowels.
 * Trema (ä), used in Aymara to indicate long vowels.
 * Colon (꞉), used in Oʼodham to indicate long vowels.

Additional letters

 * Vowel doubling, used consistently in Estonian, Finnish, Somali, Lombard and in closed syllables in Dutch, Afrikaans, and West Frisian. Example: Finnish tuuli 'wind' vs. tuli  'fire'.
 * Estonian also has a rare "overlong" vowel length but does not distinguish it from the normal long vowel in writing, as they are distinguishable by context; see the example below.
 * Consonant doubling after short vowels is very common in Swedish and other Germanic languages, including English. The system is somewhat inconsistent, especially in loanwords, around consonant clusters and with word-final nasal consonants. Examples:
 * Consistent use: byta 'to change' vs bytta  'tub' and koma  'coma' vs komma  'to come'
 * Inconsistent use: fält 'a field' and kam  'a comb' (but the verb 'to comb' is kamma)


 * Classical Milanese orthography uses consonant doubling in closed short syllables, e.g., lenguagg 'language' and pubblegh 'public'.
 * ie is used to mark the long sound in German because of to the preservation and the generalization of a historic ie spelling, which originally represented the sound . In Low German, a following e letter lengthens other vowels as well, e.g., in the name Kues.
 * A following h is frequently used in German and older Swedish spelling, e.g., German Zahn 'tooth'.
 * In Czech, the additional letter ů is used for the long U sound, and the character is known as a kroužek, e.g., kůň "horse". (It actually developed from the ligature "uo", which noted the diphthong until it shifted to .)

Other signs

 * Colon, $\langle꞉\rangle$, from Americanist phonetic notation, and used in orthographies based on it. The triangular colon $\langleː\rangle$ in the International Phonetic Alphabet derives from this.
 * Middot or half-colon, $\langleꞏ\rangle$, a more common variant in the Americanist tradition, also used in language orthographies.
 * Saltillo (straight apostrophe), used in Miꞌkmaq, as evidenced by the name itself. This is the convention of the Listuguj orthography (Miꞌgmaq), and a common substitution for the acute accent (Míkmaq) of the Francis-Smith orthography.

No distinction
Some languages make no distinction in writing. This is particularly the case with ancient languages such as Latin and Old English. Modern edited texts often use macrons with long vowels, however. Australian English does not distinguish the vowels from  in spelling, with words like 'span' or 'can' having different pronunciations depending on meaning.