The elusive vowel sound hiding in the middle of your mouth

Cultures · Published 3 October 2026 Swipe more like this →

In short: Most vowels are clearly front or back, but a rare class of sounds exists in the linguistic center. Known as the close central rounded vowel, this sound—represented by the symbol ⟨ʉ⟩—challenges how we define the very shape of our lips and tongue.

In the International Phonetic Alphabet, the close central rounded vowel, often called the 'barred u', occupies a precise anatomical position. Its height is 'close' or 'high,' meaning the tongue approaches the roof of the mouth without creating a full consonant constriction. Its backness is 'central,' placing it exactly halfway between the front and back of the vocal tract.

The true complexity of this sound lies in its 'roundedness.' While most languages use an endolabial pronunciation—where the lips protrude and the inner surfaces are exposed—some instances feature compressed or 'exolabial' rounding. In these cases, the lip margins are tense and drawn together, hiding the inner surfaces. This distinction is so subtle that the IPA lacks dedicated diacritants to differentiate them, forcing linguists to use ad hoc symbols like ⟨ʉ̫⟩ for protrusion or the recently added 2025 Unicode diacritic ⟨◌<0xE1><0xAB><0xA6>⟩ for compression.

The presence of this sound varies wildly across the globe. It appears in certain Swedish dialects and functions as an allophone in Japanese. In the language Medumba, a compressed version [ɨ<0xE1><0xB5><0x9D>] occurs where the corners of the mouth remain un-drawn. There is even a 'near-close' variation, often transcribed as ⟨ʉ̞⟩, which sits slightly lower in the mouth. Some scholars, such as John C. Wells in 'Accents of English', even use the unofficial symbol ⟨<0xE1><0xB5><0xBF>⟩ to capture these subtle shifts in vowel height and tension.

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