The close central rounded vowel is the vocalic equivalent of the rare labialized post-palatal approximant [ẅ].

The symbol ⟨ᵿ⟩, a conflation of ⟨ʊ⟩ and ⟨ʉ⟩, is used as an unofficial extension of the IPA to represent this sound by a number of publications, such as Accents of English by John C. Wells.

The close central protruded vowel is typically transcribed in IPA simply as ⟨ʉ⟩, and that is the convention used in this article.

As there is no dedicated diacritic for protrusion in the IPA, symbol for the close central rounded vowel with an old diacritic for labialization, ⟨  ̫⟩, can be used as an ad hoc symbol ⟨ʉ̫⟩ for the close central protruded vowel.

Because central rounded vowels are assumed to have protrusion, and few descriptions cover the distinction, some of the following may actually have compression.