Physiologically inspired coding strategies for cochlear implants

Cochlear implants are the first and until now the only existing prosthesis that can substitute an entire sensory system – the hearing system – nearly completely. After implantation and a period of rehabilitation, most deaf patients are able to use the telephone or listen to the radio with their cochlear implant system. Although top performing cochlear implant subjects understand speech nearly perfectly in quiet, large difficulties remain in acoustically complex environments. As well, music appraisal remains poor. It can be assumed that most of these problems arise due to the entrainment of fibers of the auditory nerve to the electrical pulse pattern applied in current stimulation strategies. Several methods were proposed to circumvent this rather artifical stimulation mode. We present methods which account for neurophysiological and neuroanatomical properties of the auditory nerve and cochlear nucleus. To quantify the outcome of these methods we developed several experimental tests.