The near-close near-back vowel, or near-high near-back vowel, is a type of vowel sound, used in some vocal languages. The IPA symbol for the near-close near-back rounded vowel is ⟨ʊ⟩. It is informally called "horseshoe u". Prior to 1989, there was an alternate IPA symbol for this sound, ⟨ɷ⟩, called "closed omega"; use of this symbol is no longer sanctioned by the IPA. In Americanist phonetic notation, the symbol ⟨ᴜ⟩ (a small capital U, not Greek lowercase upsilon) is used.
The IPA prefers the terms "close" and "open" for vowels, and the name of the article follows this. However, a large number of linguists, perhaps a majority, prefer the terms "high" and "low".
Some languages may have a near-close near-back unrounded vowel, which can be represented with ⟨ɯ̽⟩ or ⟨ʊ̜⟩ in the IPA, or a compressed vowel⟨ʊᵝ⟩.
Its vowel backness is near-back, also known as back-central or centralized back, which means the tongue is positioned as in a back vowel, but slightly further forward in the mouth.
Its vowel roundedness is sometimes rather ambiguous, but it is generally a rounded vowel, which means that the lips are rounded to a greater or lesser degree.
In the following transcriptions, an unrounded vowel is represented by the "less-rounded" diacritic [ʊ̜], and a back rounded vowel is represented by the "retracted" diacritic [ʊ̠]:
Barbosa, Plínio A.; Albano, Eleonora C. (2004), "Brazilian Portuguese", Journal of the International Phonetic Association34 (2): 227–232, doi:10.1017/S0025100304001756
Cruz-Ferreira, Madalena (1995), "European Portuguese", Journal of the International Phonetic Association25 (2): 90–94, doi:10.1017/S0025100300005223
Engstrand, Olle (1999), "Swedish", Handbook of the International Phonetic Association, Cambridge: Cambridge University Press, p. 140, ISBN0-521-63751-1
Fast Mowitz, Gerhard (1975), Sistema fonológico del idioma achual, Lima: Instituto Lingüístico de Verano
Iivonen, Antti; Harnud, Huhe (2005), "Acoustical comparison of the monophthong systems in Finnish, Mongolian and Udmurt", Journal of the International Phonetic Association35 (1): 59–71, doi:10.1017/S002510030500191X
Jones, Daniel; Ward, Dennis (1969), The Phonetics of Russian, Cambridge University Press
Kohler, Klaus J. (1999), "German", Handbook of the International Phonetic Association: A guide to the use of the International Phonetic Alphabet, Cambridge: Cambridge University Press, pp. 86–89, ISBN0-521-65236-7
Ladefoged, Peter (1999), "American English", Handbook of the International Phonetic Association, Cambridge University Press, pp. 41–44
Lee, Hyun Bok (1999), "Korean", Handbook of the International Phonetic Association, Cambridge University Press, pp. 120–122, ISBN0-521-63751-1
Mangold, Max (2005), Das Aussprachewörterbuch, Duden, p. 37, ISBN9783411040667