Structurally simple transmitreceive circuits for hearing devices are to be able to be deployed for higher frequencies as well. More particular the present invention is directed to an implant device made from polymeric material and having a stiffness gradient as well as a limited dimensional deformation, wherein the implant device has a stiffness gradient and a limited dimensional deformation and preferably is at least partially anisotropic. This slit, or slits, permits the foam, when folded upon itself, to occupy a smaller volume than the foam would occupy when folded over upon itself in the same manner, but in the absence of the slit. The supporting elements are coupled to the frame in a position to allow the strengthening apparatus to rest on the shoulders of the user during use.