|
|
Face, Speech, and Acoustics |
|
| Introduction · Program · Local Information · Registration · Contact |
I shall describe a functional modeling of face movements during speech. The data consist of 3D coordinates of 65 face markers, measured while an American speaker read a corpus. First, an arbitrary orthogonal factor analysis extracted three factors that describe marker motions (and thus face deformations) directly correlated with, respectively, vertical up/down, horizontal left/right, and horizontal front/back jaw movement. The effects of these three orthogonal factors were removed from the correlation matrix of the observed marker coordinates. Then second, a standard principal component analysis determined the fourth and fifth factors from the residual correlation matrix, ignoring higher-order principal factors. These two principal factors appear to indicate a simple and clear organization of intrinsic lip gestures. The fourth factor specifies a lip opening by spread and a closing by rounding in horizontal dimension, whereas the fifth factor captures a lip opening by protrusion and a closing by retraction in vertical dimension. Both horizontal closing and vertical opening can therefore contribute to the lip protrusion, which appears plausible considering the anatomical arrangements of the intrinsic and extrinsic lip muscles illustrated in the literature. The first three factors, which account for the effects of jaw gestures upon face deformations, explain 55% of the variance, whereas the last two factors, which accounts for intrinsic lip gestures, extract 33% of the variance. They indicate therefore a comparable degree of the influence of the two groups of gestures upon the face motions. It is noted however that in hyper-articulated nonsense VCV utterances in the corpus, both the jaw and intrinsic lip gestures are equally important and that this is not the case in the reading of a text where the jaw gestures are dominant and the lip gestures becomes much less important than the jaw gestures. Finally, I shall discuss on phonetic implications of determined factors, and on some mechanic and energetic aspects of lip motion during rapid, normal and slow utterances of the same text.