Close front rounded vowel
The close front rounded vowel, or high front rounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is /y/, and the equivalent X-SAMPA symbol is
y. Across many languages, it is most commonly represented orthographically as ⟨ü⟩ (in German, Turkish, Estonian and Basque) or ⟨y⟩ (in Danish, Norwegian, Swedish, Finnish and Albanian) but also as ⟨u⟩ (in French and a few other Romance languages and the Kernewek Kemmyn standard of Cornish); ⟨u⟩/⟨uu⟩ in Dutch; ⟨iu⟩/⟨yu⟩ (in the romanization of various Asian languages); ⟨ű⟩ (in Hungarian for the long duration version; the short version is the ⟨ü⟩ found in other European alphabets); or ⟨уь⟩ (in Cyrillic-based writing systems such as that for Chechen)
Short /y/ and long /yː/ occurred in pre-Modern Greek. In the Attic and Ionic dialects of Ancient Greek, front [y yː] developed by fronting from back /u uː/ around the 6th to 7th century BC. A little later, the diphthong /yi/ when not before another vowel monophthongized and merged with long /yː/. In Koine Greek, the diphthong /oi/ changed to [yː], likely through the intermediate stages [øi] and [øː]. Through vowel shortening in Koine Greek, long /yː/ merged with short /y/. Later, /y/ unrounded to [i], yielding the pronunciation of Modern Greek. For more information, see the articles on Ancient Greek and Koine Greek phonology.
The close front rounded vowel is the vocalic equivalent of the labialized palatal approximant [ɥ]. [y] alternates with [ɥ] in certain languages, such as French, and in the diphthongs of some languages, ⟨y̑⟩ with the non-syllabic diacritic and ⟨ɥ⟩ are used in different transcription systems to represent the same sound.
In most languages, this rounded vowel is pronounced with compressed lips ('exolabial'). However, in a few cases the lips are protruded ('endolabial').
The close front compressed vowel is typically transcribed in IPA simply as ⟨y⟩, and that is the convention used in this article. There is no dedicated diacritic for compression in the IPA. However, the compression of the lips can be shown with the letter ⟨β̞⟩ as ⟨i͡β̞⟩ (simultaneous [i] and labial compression) or ⟨iᵝ⟩ ([i] modified with labial compression). The spread-lip diacritic ⟨ ͍ ⟩ may also be used with a rounded vowel letter ⟨y͍⟩ as an ad hoc symbol, though technically 'spread' means unrounded.
Because front rounded vowels are assumed to have compression, and few descriptions cover the distinction, some of the following may actually have protrusion.
Catford notes[full citation needed] that most languages with rounded front and back vowels use distinct types of labialization, protruded back vowels and compressed front vowels. However, a few languages, such as Scandinavian ones, have protruded front vowels. One of these, Swedish, even contrasts the two types of rounding in front vowels (see near-close near-front rounded vowel, with Swedish examples of both types of rounding).
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 protruded front vowels. Another possible transcription is ⟨yʷ⟩ or ⟨iʷ⟩ (a close front vowel modified by endolabialization), but this could be misread as a diphthong.
Acoustically, this sound is "between" the more typical compressed close front vowel [y] and the unrounded close front vowel [i].