Backvowel

Backvowel is a term used in phonetics to denote a vowel produced with the tongue body positioned toward the back of the mouth. It is one dimension of vowel quality, contrasted with front vowels, which are produced with the tongue body toward the front of the oral cavity. Like other vowel features, backness is part of a multi-dimensional space that also includes tongue height and, for many languages, lip rounding.

Back vowels can be rounded or unrounded. Commonly cited back vowels include the high back rounded [u], the near-close back rounded [ʊ], the mid back rounded [o], the open-mid back rounded [ɔ], and the open back unrounded [ɑ]. Other languages have back unrounded vowels such as [ɯ] and [ɤ], which occupy the high and mid back regions respectively. The exact inventory of back vowels varies across languages, and some languages lack certain height levels or contrasts. Backness is a separate property from rounding, so both rounded and unrounded back vowels exist within a language.

In language phonology, back vowels contrast with front vowels and may participate in harmony processes or other vowel-phonation patterns. The backness dimension often interacts with rounding and with the presence of central vowels, yielding a range of vowel inventories. While some languages have rich back-vowel systems, others have only a small number of back vowels or merge them with neighboring front or central vowels.

Notationally, backness is represented on the horizontal axis of the vowel space in many descriptions, with back vowels occupying the posterior portion of the chart. IPA symbols are used to transcribe back vowels, just as they are for front and central vowels.