Totally implantable active middle ear implants: ten years' experience at the University of Tübingen.

Active middle ear implants do not produce acoustic sounds but, rather, micromechanical vibrations. The stimulating signal does not leave the transducer as sound, but as a mechanical vibration, directly coupled to the auditory system and bypassing the normal route via air. In this paper, we review our experience with the TICA and the Carina middle ear implants. Both are totally implantable and are coupled to the ossicular chain or to perilymph. The design requirements for electronic hearing implants for patients with conductive hearing loss differ from those for sensorineural hearing loss. Conductive hearing loss requires an implant that replaces impedance transformation and acts as an impedance transforming implant (ITI). In many respects, there are fewer demands on an ITI than on an electronic hearing aid for patients with sensorineural hearing loss.