Close back rounded vowel

The close back rounded vowel, or high back rounded vowel, is a type of vowel sound used in many spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is.
In most languages, this rounded vowel is pronounced with protruded lips. However, in a few cases the lips are compressed.
alternates with labio-velar approximant in certain languages, such as French, and in the diphthongs of some languages, with the non-syllabic diacritic and are used in different transcription systems to represent the same sound.

Close back protruded vowel

The close back protruded vowel is the most common variant of the close back rounded vowel. It is typically transcribed in IPA simply as . As there is no dedicated IPA diacritic for protrusion, the symbol for the close back rounded vowel with an old diacritic for labialization,, can be used as an ad hoc symbol. Another possible transcription is or, but that could be misread as a diphthong.

Close back compressed vowel

Some languages, such as Japanese and Swedish, have a close back vowel that has a distinct type of rounding, called compressed or exolabial. Only Shanghainese is known to contrast it with the more typical protruded close back vowel, but the height of both vowels varies from close to close-mid.
As there are no diacritics in the IPA to distinguish protruded and compressed rounding, an old diacritic for labialization,, will be used here as an ad hoc symbol for compressed back vowels. It was only added to Unicode in 2025, however, and it may take some time for font support to catch up. Compression of the lips can be shown with the letter as or, though that can suggest that the vowel is a diphthong.