Roughly 1000 frames of cineradiographic and labiofilm data on the vocal tract corresponding to 10 French sentences uttered by two speakers have been analyzed statistically. The analysis resulted in an articulatory model consists of a limited number of linear components. With this model the temporal variations of the vocal-tract shapes are described by the frame-to-frame samples of the articulatory parameters. We observe that "target" parameter values for the same vowel vary significantly pre- sumably due to different phonetic contexts. An acoustic calculation with the model predicts that a particular pair of articulators can compensate acoustically each other. For example, by an appropriate adjustment of the tongue-dorsal position, the model is capable of producing the same F1-F2 pattern for different jaw position, or vice-versa. The compensation between the jaw and the dorsal positions, however, is possible only for unrounded vowels. In the case of rounded vowels, the jaw position can be compensated by the lip aperture. The measured "target" values of the paired parameters indicated a linear relationship, suggesting that the speakers actually exploit the inter-articulator compensation in the speech production. This explains the observed large "target" value variability. The comparison of parameter trajectories for the same sentences uttered by the two speakers indicates more similitude than difference, suggesting mat the manner of the production involving the compensatory articulation could be relatively invariant.