In phonetics, vowel roundedness identified to a amount of rounding in a lips during the articulation of a vowel. it is labialization of a vowel. When a rounded vowel is pronounced, the lips go forward to a circular opening, in addition to unrounded vowels are pronounced with the lips relaxed. In near languages, front vowels tend to be unrounded, together with back vowels tend to be rounded. However, some languages, such(a) as French, German and Icelandic, distinguish rounded and unrounded front vowels of the same height degree of openness, and Vietnamese distinguishes rounded and unrounded back vowels of the same height. Alekano has only unrounded vowels. In the International Phonetic Alphabet vowel chart, rounded vowels are the ones thaton the correct in each pair of vowels. There are also diacritics, 0339 ◌̹ COMBINING adjustment HALF RING BELOW and 031C ◌̜ COMBINING LEFT HALF RING BELOW, to indicate greater and lesser degrees of rounding, respectively. Thus [o̜] has less rounding than cardinal [o], and [o̹] has more closer to the rounding of cardinal [u]. These diacritics can also be used with unrounded vowels: [ɛ̜] is more spread less rounded than cardinal [ɛ], and [ɯ̹] is less spread than cardinal [ɯ].

Spread and neutral

The lip position of unrounded vowels may be classified into two groups: spread and neutral. Front vowels are commonly pronounced with the lips spread, and the spreading becomes more significant as the height of the vowel increases. Open vowels are often neutral, i.e. neither rounded nor spread, because the open jaw enables for limited rounding or spreading of the lips. This is reflected in the IPA's definition of the cardinal ], which is unrounded yet not spread either.