Longitudinal coupling in the basilar membrane

A systematic and detailed study of the longitudinal coupling exhibited by t he basilar membrane (BM) was performed in the excised gerbil cochlea. Contr ary to the notion that the adjacent regions of the BM are decoupled from ea ch other, the data indicate that: (a) the BM exhibits longitudinal coupling ; (b) the length of the coupled region increases from base to apex of the c ochlea; and (c) the cells of the organ of Corti (OC) increase the overall c oupling exhibited by the BM. Modeling results show that, at a given locatio n, longitudinal coupling increases the effective stiffness of the OC near t he characteristic frequency. Therefore, the effect of longitudinal coupling cannot be neglected in the region of the peak of the traveling wave.