249

The Vibrant Soundbridge (VSB) is a middle ear hearing implant designed to augment hearing, using “direct-drive” stimulation of the auditory system via amplification of ossicular motion. The implant system is currently indicated for adults with sensorineural hearing loss of moderate-to-severe degree. Recently, however, the VSB has been applied to conductive and mixed hearing losses by placing the floating mass transducer (FMT) in the round window niche to deliver mechanical excitation to the cochlea. This novel stimulation of the cochlea may provide a level of hearing to persons with a variety of middle ear pathologies that may preclude the use of a traditional hearing aid, either due to medical reasons or because of very high acoustic hearing thresholds. Because residual cochlear hearing is often quite good in these cases, excitation of the cochlea may offer usable auditory information even to persons with poor air conduction thresholds. Early pre-clinical and clinical evaluations of mechanical excitation of the cochlea via the round window have included laserdoppler- vibrometry, auditory brainstem response, and electrocochleographic measures. Data collected to date have suggested the practical equivalence of cochlear stimulation via ossicular and round window pathways. Those data will be reviewed here. In addition, alternative technical solutions to direct acoustic cochlear stimulation will be presented. The new techniques to stimulate the cochlea may also be suitable for providing fine structure information using combined electrical and mechanical stimulation.