“Laws” for lips

Abstract

Among the main lip-geometry measures such as: • - frontal: width, height, area; • - lateral: upper, lower and corner protrusions; lip horn opening and depth; some relations are of interest for acoustic, articulatory and practical modeling. In order to maximize the proper movements of the lips themselves, a corpus was designed to explore the maximum lip manoeuvre space for French vowels (5 speakers) using naturally close jaw conditions (consonantal [s] and [∫] contexts). Since Fromkin's (1964) “[i,a,u] angle”, it has been well known, that for front views, both width and height are needed for calculation of lip area: Area/(Width × Height) = constant (somehow speaker dependent: around 0.75). Proposals to calculate are from width or height alone are thus discarded. Profile protrusions are naturally strongly correlated, and so is lip horn depth with corner protrusion. So we can choose corner as the pivot in lip horn profile modeling. But, for such a modeling, the most interesting relation between front and profile views is the inverse correlation between width and protrusion (on condition that corner protrusion is chosen). Hence prediction of area is possible through profile measurements namely with height (or opening) and corner protrusion: Area/[Height × (Ref - corner protrusion)] = constant (where Ref. is the chosen reference for protrusion measures).