In this paper , the application of the Equilibrium Point Hypothesis— originally proposed by Feldman for the control of limb movements— to speech control is analysed . In the first part , physiological data published in the literature which argue in favour of such control for the tongue are presented and the possible role of this motor process in a global control model of the tongue is explicated . In the second part , using the example of the acoustic variability associated with vowel reduction , we focus on how the Equilibrium Point Hypothesis could help to search for physical regularities associated with a phonological sequence produced under variable speech conditions : the equilibrium point sequence could be invariant while the level of cocontraction and the timing of the commands could vary with the speech condition .