In phonetics, a vowel is a sound in spoken language that is characterized by an open configuration of the vocal tract, in contrast to consonants, which are characterized by a constriction or closure at one or more points along the vocal tract. The word vowel comes from the Latin word vocalis, meaning "uttering voice" or "speaking". Vowels usually form the peak or nucleus of a syllable, whereas consonants form the onset and coda. However, some languages allow sounds that wouldn't normally be classified as vowels to form the nucleus of a syllable, such as the sound of m in the English word prism, or the sound of r in the Czech word vrba (meaning "willow"). Sometimes vowels are defined by whether they form the nucleus of a syllable, and by that criterion these sounds are vowels, but usually sounds that can form the nucleus of a syllable are called sonorants. (In some languages, such as Tashlhyt Berber and Oowekyala, non-sonorant consonants can also form the nucleus of a syllable.)
Vowel space has many dimensions. The three most significant are height, backness, and roundedness.
The articulatory features that distinguish different vowels in a language are said to determine the vowel's quality. Daniel Jones developed the cardinal vowel system to describe vowels in terms of the common features height, backness and roundedness. There are however still more possible features of vowel quality.
Height refers to the position of the tongue relative to the roof of the mouth. In high vowels, such as [i] and [u], the tongue is positioned high in the mouth, whereas in low vowels, such as [a], the tongue is positioned low in the mouth. Sometimes the terms open and close are used as synonyms for low and high for describing vowels. The International Phonetic Alphabet identifies seven different vowel heights, although no known language distinguishes all seven:
Backness refers to the tongue position during the articulation of a vowel relative to the back of the mouth. In front vowels, such as [i], the tongue is positioned forward in the mouth, whereas in back vowels, such as [u], the tongue is positioned towards the back of the mouth. The International Phonetic Alphabet identifies five different degrees of vowel backness, although no known language distinguishes all five:
Roundedness refers to whether the lips are rounded, or not. In most languages, roundedness is just an additional feature of back vowels, and not a distinctive feature. However, some languages distinguish roundedness and backness separately, such as French, German, and some dialects of English. Different kinds of rounded vowels are also possible, as in Swedish, which has "pursed lips" rounded vowels as well as "compressed lips" rounded vowels.
Nasalization refers to whether some of the air escapes through the nose. In nasal vowels, the velum is lowered, and some air travels through the nasal cavity as well as the mouth. An oral vowel is a vowel in which all air escapes through the mouth. French and Portuguese contrast nasal and oral vowels.
Tenseness/checked vowels vs. free vowels
Tenseness is used to describe the opposition of tense vowels as in leap, suit vs. lax vowels as in lip, soot. This opposition is thought to be a result of greater muscular tension, though this has not been confirmed by phonetic experiments.
Unlike the other features of vowel quality, tenseness is only applicable to the few languages that have this opposition (mainly Germanic languages, e.g. English), whereas the vowels of the other languages (e.g. Spanish) cannot be described with respect to tenseness in any meaningful way.
In most Germanic languages, lax vowels can only occure in closed syllables. Therefore, they're also known as checked vowels , whereas the tense vowels are called free vowels since they can occur in open syllables.
Voicing describes whether the vocal cords are vibrating during the articulation of a vowel. Most languages only have voiced vowels, but several Native American languages, such as Cheyenne and Totonac, contrast voiced and devoiced vowels. Vowels are devoiced in whispered speech. In Japanese and Quebec French, vowels that are between voiceless consonants are often devoiced.
Creaky voice, breathy voice, and murmured voice are phonation types that are used contrastively in some languages. Often, these co-occur with tones or stress patterns; in the Mon language, vowels pronounced in "high tone" are also produced with creaky voice. In cases like this, it can be unclear whether it is the tone, the voicing type, or the pairing of the two that is being used for phonemic contrast.
Tongue root retraction
Retracted tongue root is a feature common in some groups of African languages. This contrast is used extensively in Maa and other East African languages. The contrast between advanced tongue root and retracted tongue root resembles the lax/tense contrast acoustically, but they are articulated differently.
Secondary narrowings in the vocal tract
Pharyngealisation occurs in some languages; Sedang uses this contrast.
The features of vowel prosody are often described independently from vowel quality. In non-linear phonetics, they are located on parallel layers. The features of vowel prosody are usually considered not to apply to the vowel itself, but to the syllable.
Length or quantity refers to the duration of the vowel. Note that this feature may also be described as a feature of the vowel quality, not of the prosody. Japanese, Arabic and Latin have a two-way contrast between short and long vowels. Estonian and Wichita have a three-way contrast among short, half-long, and long vowels. Long vowels are written in the IPA with a triangular colon, which has two equilateral triangles pointing at each other in place of dots (e.g. [iː]). The IPA symbol for half-long vowels is the triangular colon without the lower triangle (e.g. [iˑ]).
Intonation refers to the pitch of a syllable. This feature depends on the syntax. In the tonal languages the intonation depends additionally on the morphology.
Stress refers to the emphasis given to a syllable.
Monophthongs, diphthongs, triphthongs
A vowel sound whose quality doesn't change over the duration of the vowel is called a monophthong. Monophthongs are sometimes called "pure" or "stable" vowels. A vowel sound that glides from one quality to another is called a diphthong, and a vowel sound that glides between three qualities is a triphthong.
All languages have monophthongs and many languages have diphthongs, but triphthongs or vowel sounds with even more target qualities are relatively rare cross-linguistically. English has all three types: the vowel sound in hit is a monophthong [ɪ], the vowel sound in boy is in most dialects a diphthong [ɔɪ], and the vowel sounds of way [weɪ], flower (BrE [aʊə] AmE [aʊɚ]) form a triphthong, although the particular qualities vary by dialect.
In phonology, diphthongs and triphthongs are distinguished from sequences of monophthongs by whether or not the vowel sound may be analyzed into different phonemes or not. For example, the vowel sounds in a two-syllable pronunciation of the word flower (BrE [flaʊə] AmE [flaʊɚ]) phonetically form a triphthong, but are phonologically a sequence of a diphthong (represented by the letters <ow>) and a monophthong (represented by the letters <er>). Some linguists use the terms diphthong and triphthong only in this phonemic sense.
The name "vowel" is often used for the symbols used for representing vowel sounds in a language's writing system, particularly if the language uses an alphabet. In the Latin alphabet, the vowel letters are usually A, E, I, O, U, and in some languages Y, as in English and W, as in Welsh.
There is necessarily not a direct one-to-one correspondence between the vowel sounds of a language and the vowel letters. Many languages that use a form of the Latin alphabet have more vowel sounds than can be represented by the standard set of five vowel letters. In the case of English, the five primary vowel letters can represent both long and short vowel sounds (some of the long vowel sounds in English are actually diphthongs). Furthermore, in English some vowel sounds are represented by combinations of vowel letters, such as the ea in beat or by a vowel letter and an approximant letter, as the ow in how, or the er in her.
Other languages cope with the limitation in the number of Latin vowel letters in similar ways. Many languages, like English, make extensive use of combinations of vowel letters to represent various sounds. Other languages add diacritical marks to vowels, such as accents or umlauts, to represent the variety of possible vowel sounds. Some languages have also constructed additional vowel letters by modifying the standard Latin vowels in other ways, such as ś or Ý that are found in some of the Scandinavian languages. The International Phonetic Alphabet has a set of 28 symbols to represent the range of basic vowel qualities, and a further set of diacritics to denote variations from the basic vowel.
Vowels in languages
The semantic significance of vowels varies widely depending on the language. In some languages, particularly Semitic languages, vowels mostly serve to denote inflections. This is similar to English man vs. men. In fact, the alphabets used to write the Semitic languages, such as the Hebrew alphabet and the Arabic alphabet, do not ordinarily mark all the vowels. These alphabets are called abjads. Although it is possible to construct simple English sentences that can be understood without written vowels (cn y rd ths?), extended passages of English lacking written vowels are difficult if not impossible to completely understand (consider dd, which could be any of add, aided, dad, dada, dead, deed, did, died, dodo, dud, dude, eddie, iodide, or odd).
In most languages, vowels are an unchangeable part of the words, as in English man vs. moon which are not different inflectional forms of the same word, but different words. Vowels are especially important to the structures of words in languages that have very few consonants (like Polynesian languages such as Maori and Hawaiian), and in languages whose inventory of vowels is larger than its inventory of consonants (like Sedang, a relative of Vietnamese, which contrasts 55 different vowel qualities).
Most languages have 3–7 vowels, the following 5-vowel system being the most common:
This particular configuration is common because it makes the most efficient use of the vowel space, so slight variations in a vowel are not easily confused for a different sound. Spanish and Modern Greek, for example, have this vowel system; Latin had a similar system that also distinguished between long and short vowels, although that distinction wasn't made in written Latin; it is for this reason that the Latin alphabet has five vowel letters. All languages have at least two vowels; the Tshwizhyi and Abzhui dialects of Abkhaz contrasts only /a/ and /
i/, with significant allophony. (Some linguists claim that it is possible to posit only one vowel in some Abkhaz dialects, though the consensus seems to be that that is stretching things a bit.) Three-vowel systems have been noted in a number of languages. These include:
A few languages, such as Navajo, have four-vowel systems that lack /u/ but there is no known natural language that lacks some form of a. At the other end of the spectrum, languages with more than twelve vowels are relatively uncommon, although some widely-spoken languages have large vowel inventories, particularly Germanic languages. For example, English has 14–16 vowels (including diphthongs) depending on dialect, and Swedish has the most distinct vowel qualities in the height-backness-roundedness spectrum, with 17 different monophthongs. French has 16 vowel qualities (including nasals), and the previously-mentioned Sedang holds the known record with 55 different vowels.
Written vowels in different writing systems
Arabic: دَ دِ دُ دَا دَى دِي دُو
Korean: ㅏ ㅐ ㅑ ㅒ ㅓ ㅔ ㅕ ㅖ ㅗ ㅘ ㅙ ㅚ ㅛ ㅜ ㅝ ㅞ ㅟ ㅠ ㅡ ㅢ ㅣ
Russian: hard: А О У Ы Э ; soft: Я Ё Ю И Е
Japanese: normal: あいうえお grammatical: へを