Editing Roundedness (section)

==Labialization==
Protruded rounding is the vocalic equivalent of consonantal [[labialization]]. Thus, rounded vowels and labialized consonants affect one another by [[assimilation (linguistics)|phonetic assimilation]]: Rounded vowels labialize consonants, and labialized consonants round vowels.

In many languages, such effects are minor phonetic detail, but in others, they become significant. For example, in [[Standard Chinese phonology|Standard Chinese]], the vowel {{IPA|/ɔ/}} is pronounced {{IPA|[u̯ɔ]}} after labial consonants,{{Citation needed|date=July 2009}} an allophonic effect that is so important that it is encoded in [[pinyin]] transliteration: alveolar {{IPA|/tu̯ɔ˥/}} {{IPAc-cmn|d|uo|1}} ({{Zh|p=duō|labels=no|c=多|s=|t=}}) 'many' vs. labial {{IPA|/pu̯ɔ˥/}} {{IPAc-cmn|b|o|1}} ({{Zh|p=bō|labels=no|c=波}}) 'wave'. In [[Vietnamese language|Vietnamese]], the opposite assimilation takes place: velar codas {{IPA|/k/}} and {{IPA|/ŋ/}} are pronounced as labialized {{IPA|[kʷ]}} and {{IPA|[ŋʷ]}} or even [[labial-velar consonant|labial-velar]] {{IPA|[kp]}} and {{IPA|[ŋm]}}, after the rounded vowels {{IPA|/u/}} and {{IPA|/o/}}.{{Citation needed|date=July 2009}}

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. Thus, Sepik {{IPA|[ku]}} and {{IPA|[ko]}} are phonemically {{IPA|/kwɨ/}} and {{IPA|/kwə/}}.{{Citation needed|date=July 2009}} In the extinct [[Ubykh phonology|Ubykh]], {{IPA|[ku]}} and {{IPA|[ko]}} were phonemically {{IPA|/kʷə/}} and {{IPA|/kʷa/}}.{{Citation needed|date=July 2009}} 

A few ancient [[Indo-European languages]] like [[Latin]] had [[labialized velar consonant]]s.{{sfnp|Allen|1978}}