Editing Vowel (section)

===Height===<!-- This section is linked from [[Latin spelling and pronunciation]] -->
Theoretically, vowel height refers to the vertical position of either the tongue or the jaw (depending on the model) relative to either the roof of the mouth or the aperture of the [[jaw]]. In practice, however, it refers to the first [[formant]] (lowest resonance of the voice), abbreviated F1, which is associated with the height of the tongue. There are two terms commonly applied to refer to two degrees of vowel height: in '''close vowels''', also known as '''high vowels''', such as {{IPA|[i]}} and {{IPA|[u]}}, the first formant is consistent with the tongue being positioned close to the palate, high in the mouth, whereas in '''open vowels''', also known as '''low vowels''', such as {{IPA|[a]}}, F1 is consistent with the jaw being open and the tongue being positioned low in the mouth. Height is defined by the inverse of the F1 value: the higher the frequency of the first formant, the lower (more open) the vowel.{{efn|According to [[Peter Ladefoged]], traditional articulatory descriptions such as height and backness "are not entirely satisfactory", and when phoneticians describe a vowel as high or low, they are in fact describing an acoustic quality rather than the actual position of the tongue.<ref>Ladefoged, Peter (2006) ''A Course in Phonetics (Fifth Edition)'', Boston, MA: Thomson Wadsworth, p. 189.</ref>}} In [[John Esling]]'s usage, where [[front vowel|fronted vowels]] are distinguished in height by the position of the jaw rather than the tongue, only the terms 'open' and 'close' are used, as 'high' and 'low' refer to the position of the tongue.

The [[International Phonetic Alphabet]] has letters for six degrees of vowel height for full vowels (plus the reduced mid vowel {{IPA|[ə]}}), but it is extremely unusual for a language to distinguish this many degrees without other attributes. The IPA letters distinguish (sorted according to height, with the top-most one being the highest and the bottom-most being the lowest):

* [[close vowel|close]] ({{aka}} high): i y ɨ ʉ ɯ u
* [[near-close vowel|near-close]] ({{aka}} near-high): ɪ ʏ ʊ
* [[close-mid vowel|close-mid]] ({{aka}} high-mid): e ø ɘ ɵ ɤ o
* [[mid vowel|mid]]: (the reduced vowel {{IPA|[ə]}})
* [[open-mid vowel|open-mid]] ({{aka}} low-mid): ɛ œ ɜ ɞ ʌ ɔ
* [[near-open vowel|near-open]] ({{aka}} near-low): æ (plus the reduced vowel {{IPA|[ɐ]}})
* [[open vowel|open]] ({{aka}} low): a ɶ ɑ ɒ

The letters {{angbr IPA|e, ø, ɘ, ɵ, ɤ, o}} are defined as close-mid but are commonly used for true [[mid vowel]]s. If more precision is required, true mid vowels may be written with a lowering or raising diacritic: {{angbr IPA|e̞, ɘ̞, ø̞, ɵ̞, ɤ̞, o̞}} or {{angbr IPA|ɛ̝ œ̝ ɜ̝ ɞ̝ ʌ̝ ɔ̝}}.

The [[Kensiu language]], spoken in Malaysia and Thailand, is highly unusual in contrasting true mid vowels with both close-mid and open-mid vowels, without any additional parameters such as length, roundness or ATR. The front vowels, {{IPA|/i ɪ e e̞ ɛ/}}, along with open {{IPA|/a/}}, make a six-way height distinction; this holds even for the nasal vowels. A few varieties of [[German language|German]] have been reported to have five contrastive vowel heights that are independent of length or other parameters. For example, the [[Austro-Bavarian|Bavarian]] dialect of [[Amstetten, Lower Austria|Amstetten]] has thirteen long vowels, which have been analyzed as four vowel heights (close, close-mid, mid, open-mid) each among the front unrounded, front rounded, and back rounded vowels, along with an open vowel for a fifth height: {{IPA|/i e ɛ̝ ɛ/, /y ø œ̝ œ/, /u o ɔ̝ ɔ/, /a/}}. Apart from the aforementioned [[Kensiu language]], no other language is known to contrast more than four degrees of vowel height.

The parameter of vowel height appears to be the primary cross-linguistic feature of vowels in that all [[spoken language]]s that have been researched till now use height as a contrastive feature. No other parameter, even backness or rounding (see below), is used in all languages. Some languages have [[vertical vowel system]]s in which at least at a phonemic level, only height is used to distinguish vowels.