Roundedness

In phonetics, vowel roundedness refers to the amount of rounding in the lips during the articulation of a vowel. That is, it is vocalic labialization. When pronouncing a rounded vowel, the lips form a circular opening, while unrounded vowels (also called spread vowels) are pronounced with the lips relaxed. In most languages, front vowels tend to be unrounded, while back vowels tend to be rounded. But some languages, such as French and German, distinguish rounded and unrounded front vowels of the same height, while, for example, Vietnamese distinguishes rounded and unrounded back vowels of the same height.

In the International Phonetic Alphabet vowel chart, rounded vowels are the ones that occur on the right in each pair of vowels. There are also diacritics, respectively , to indicate greater or lesser degrees of rounding. The 'more' and 'less rounded' diacritics are sometimes also used with consonants to indicate degrees of labialization.

Types of rounding

The distinction between protruded and compressed holds for the semivowels and as well as labialization. In Akan, for example, the is compressed, as are labio-palatalized consonants as in Twi "Twi" and adwuma "work", whereas and simply labialized consonants are protruded. In Japanese, the is compressed rather than protruded, paralleling the Japanese . The distinction applies marginally to other consonants. In Southern Teke, the sole language reported to have a phonemic , the labiodental sound is "accompanied by strong protrusion of both lips", whereas the found as an allophone of before in languages such as English is not protruded, as the lip contacts the teeth along its upper or outer edge. And in at least one account of speech acquisition, a child's pronunciation of clown involves a lateral with the upper teeth contacting the upper-outer edge of the lip, but in crown a non-lateral is pronounced with the teeth contacting the inner surface of the protruded lower lip.

Roundedness and labialization

In many languages such effects are minor phonetic detail, but in some cases they become significant. For example, in Mandarin Chinese, the unrounded vowel is pronounced after labial consonants, an allophonic effect salient enough to be encoded in pinyin transliteration: velar he vs. labial bo. In Vietnamese, the opposite assimilation takes place: velar codas and are pronounced as labialized and , or even labial-velar and , after the rounded vowels and . In the Northwest Caucasian languages of the Caucasus and the Sepik languages of Papua New Guinea, historically rounded vowels have become unrounded, with the rounding being taken up by the consonant, so that, for example, Sepik and are phonemically and ; similarly, Ubykh and are phonemically and .

Notes