[Determinants of the effectiveness of electric stimulation of the auditory nerve with cochlear implants: II. Configuration of the stimulating electrodes].

The influence of the electrode configuration on the efficacy of the electrical stimulation were investigated in the auditory nerve. For this purpose normal hearing cats were deafened by intrascalar application of neomycin and stimulated by a NUCLEUS-22 implant. Stimulation was performed in monopolar, bipolar and tripolar mode with all electrodes of the implant. The smallest thresholds were determined for monopolar stimulation, followed by tripolar and bipolar stimulation. The most focused stimulation was achieved by tripolar stimulation, followed by bipolar and monopolar stimulation. Tripolar stimulation is therefore suitable for beam forming in electrical stimulation of the auditory nerve.