Back vowel

Back vowels are vowel sounds articulated with the primary tongue constriction (the highest point of the tongue body) located toward the back of the oral cavity, near the velum (or in some cases further back in the vocal tract toward the pharynx), relative to front and central vowels.

Back vowels are common across languages. In the PHOIBLE 2.0 convenience sample of phonological inventories, [u] and [o] are among the most frequently listed vowel segments, occurring in 88% and 60% of inventories in the sample, respectively. Back vowels are often, but not always, rounded: cross-linguistically, non-low back vowels are commonly rounded (e.g. [u o]), while low vowels are often unrounded; front rounded vowels and back unrounded vowels also occur, but are less common.