There is some experimental evidence that the mechanical cochlear function is strongly influenced by the efferent innervation of outer-hair-cell stereocilia (OHCS). [See, e.g., D. C. Mountain, Science 210, 71–72 (1980); J. H. Siegel and D. O. Kim, Hear. Res. 6, 171–182 (1982).] This suggests that the various nonlinear and active mechanical features of the cochlear response may be mainly rooted in the OHCS. We propose a specific nonlinear feedback model for the mechanics of the OHCS, which is a generalization of a linear model proposed by Mountain. It gives formally the combination of negative resistance and nonlinear damping used in previous calculations [S. Koshigoe and A. Tubis, J. Acoust. Soc. Am. Suppl. 1 71, S17 (1982)]. The parameters of the model are determined so as to account for experimental measurements of the basilar membrane response as well as stimulated and spontaneous emissions in the ear canal. [This work was supported by NSF.]