Unstressed vocalism of English
Vocalism - the system of vowels used in a particular language.
In phonetics, a vowel is a sound in spoken language, such as English ah! [ɑː] or oh! [oʊ], pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as English sh! [ʃː], where there is a constriction or closure at some point along the vocal tract. A vowel is also understood to be syllabic: an equivalent open but non-syllabic sound is called a semivowel.
In all languages, vowels form the nucleus or peak of syllables, whereas consonants form the onset and (in languages which have them) coda. However, some languages also allow other sounds to form the nucleus of a syllable, such as the syllabic l in the English word table [ˈteɪ.bl̩] (the stroke under the l indicates that it is syllabic; the dot separates syllables), or the r in Serbian vrt [vr̩t] "garden".
We might note the conflict between the phonetic definition of 'vowel' (a sound produced with no constriction in the vocal tract) and the phonological definition (a sound that forms the peak of a syllable). The approximants [j] and [w] illustrate this conflict: both are produced without much of a constriction in the vocal tract (so phonetically they seem to be vowel-like), but they occur on the edge of syllables, such as at the beginning of the English words 'yes' and 'wet' (which suggests that phonologically they are consonants). The American linguist Kenneth Pike suggested the terms 'vocoid' for a phonetic vowel and 'vowel' for a phonological vowel, so using this terminology, [j] and [w] are classified as vocoids but not vowels.
The word vowel comes from the Latin word vocalis, meaning "speaking", because in most languages words and thus speech are not possible without vowels. Vowel is commonly used to mean both vowel sounds and the written symbols that represent them.
Vowels v • d • e
Close i · y
ɨ · ʉ
ɯ · u
ɪ · ʏ
ɪ̈ · ʊ
e · ø
ɘ · ɵ
ɤ · o
ɛ · œ
ɜ · ɞ
ʌ · ɔ
a · ɶ
ɑ · ɒ
Where symbols appear in pairs, the one to the right represents
a rounded vowel. Vowel length is indicated by appending ː.
X-rays of Daniel Jones' [i, u, a, ɑ].
The articulatory features that distinguish different vowel sounds 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 (vertical dimension), backness (horizontal dimension) and roundedness (lip position). These three parameters are indicated in the schematic IPA vowel diagram on the right. There are however still more possible features of vowel quality, such as the velum position (nasality), type of vocal fold vibration (phonation), and tongue root position.
Vowel height is named for the vertical position of the tongue relative to either the roof of the mouth or the aperture of the jaw. 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. The IPA prefers the terms close vowel and open vowel, respectively, which describes the jaw as being relatively open or closed. However, vowel height is an acoustic rather than articulatory quality, and is defined today not in terms of tongue height, or jaw openness, but according to the relative frequency of the first formant (F1). The higher the F1 value, the lower (more open) the vowel; height is thus inversely correlated to F1.
The International Phonetic Alphabet identifies seven different vowel heights:
close vowel (high vowel)
open vowel (low vowel)
True mid vowels do not contrast with both close-mid and open-mid in any language, and the letters [e ø ɤ o] are typically used for either close-mid or mid vowels.
Although English contrasts all six contrasting heights in its vowels, these are interdependent with differences in backness, and many are parts of diphthongs. It appears that some varieties of German have five contrasting vowel heights independently of length or other parameters. The Bavarian dialect of Amstetten has thirteen long vowels, reported to distinguish four heights (close, close-mid, mid, and near-open) each among the front unrounded, front rounded, and back rounded vowels, plus an open central vowel: /i e ɛ̝ æ̝/, /y ø œ̝ɶ̝/, /u o ɔ̝ɒ̝/, /a/. Otherwise, the usual limit on the number of contrasting vowel heights is four.
The parameter of vowel height appears to be the primary feature of vowels cross-linguistically in that all languages use height contrastively. No other parameter, such as front-back or rounded-unrounded (see below), is used in all languages. Some languages have vertical vowel systems in which, at least at a phonemic level, only height is used to distinguish vowels.
Tongue positions of cardinal front vowels with highest point indicated. The position of the highest point is used to determine vowel height and backness
Vowel backness is named for the position of the tongue 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. However, vowels are defined as back or front not according to actual articulation, but according to the relative frequency of the second formant (F2). The higher the F2 value, the fronter the vowel; backness is thus inversely correlated to F2.
The International Phonetic Alphabet identifies five different degrees of vowel backness:
Although English has vowels at all five degrees of backness, there is no known language that distinguishes all five without additional differences in height or rounding.
Roundedness refers to whether the lips are rounded or not. In most languages, roundedness is a reinforcing feature of mid to high back vowels, and is not distinctive. Usually the higher a back vowel is, the more intense the rounding. However, some languages treat roundedness and backness separately, such as French and German (with front rounded vowels), most Uralic languages (Estonian has a rounding contrast for /o/ and front vowels), Turkic languages (with an unrounded /u/), Vietnamese (with back unrounded vowels), and Korean (with a contrast in both front and back vowels).
Nonetheless, even in languages such as German and Vietnamese, there is usually some phonetic correlation between rounding and backness: front rounded vowels tend to be less front than front unrounded vowels, and back unrounded vowels tend to be less back than back rounded vowels. That is, the placement of unrounded vowels to the left of rounded vowels on the IPA vowel chart is reflective of their typical position.
Different kinds of labialization are also possible. In mid to high rounded back vowels the lips are generally protruded ("pursed") outward, a phenomenon known as exolabial rounding because the insides of the lips are visible, whereas in mid to high rounded front vowels the lips are generally "compressed", with the margins of the lips pulled in and drawn towards each other, a phenomenon known as endolabial rounding. However, not all languages follow this pattern. The Japanese /u/, for example, is an endolabial (compressed) back vowel, and sounds quite different from an English exolabial /u/. Swedish and Norwegian are the only two known languages where this feature is contrastive, having both endo- and exo-labial close front rounded vowels and close central rounded vowels, respectively. In many phonetic treatments, both are considered types of rounding, but some phoneticians do not believe that these are subsets of a single phenomenon of rounding, and prefer instead the three independent terms rounded (exolabial), compressed (endolabial), and spread (unrounded).