A cochlear implant electrode assembly device (10) comprising an elongate electrode carrier member (11), a stiffening element (15), and a stiffening sheath (16) that at least partially envelops the elongate member (11). The member (11) is made of a resiliently flexible first material and has a plurality of electrodes (12) mounted thereon. The member (11) has a first configuration that allows it to be inserted into an implantee's cochlea (30). The member (11) also has a second configuration wherein the member is curved to match an inside surface of the cochlea (30), and at least one intermediate configuration between the first and second configurations. Both the stiffening element (15) and sheath (16) are made of a material that is relatively stiffer than the member (11). The stiffening element (15) and the stiffening sheath (16) in combination bias the elongate member (11) into the first configuration. If either the stiffening element (15) or the stiffening sheath (16) is removed or deactivated, the elongate member (11) adopts an intermediate configuration.