An arrangement for operating a cochlear implant system is described. Stimulation signals are applied to stimulation electrodes in a cochlear implant electrode with an initial signal format using biphasic electrical stimulation pulses. One or more undesired somatic responses to the stimulation pulses are identified. The one or more undesired somatic responses are reduced by selecting an adapted signal format using charge-balanced triphasic electrical stimulation pulses to apply stimulation signals to one or more of the stimulation electrodes.