Phonological degrees of labiality

A [+round] or [labial] feature is traditionally viewed as an elementary phonological unit that has different phonetic realizations depending on the height and backness of the segment that realizes it (McCarthy 1988, Clements & Hume 1995, Halle 1995, Kaun 1995, among others). In this article, I make two claims: (i) qualitatively different lip gestures are phonological in some languages, and (ii) there is more faithfulness to more extreme lip gestures.