1. A method of processing sound signals for use in generating electrical stimuli for an auditory prosthesis, said method including the steps of processing a sound signal according to a predetermined instruction set to produce a set of stimulus instructions for an implanted electrode array, characterised in that the predetermined instruction set operates so as to produce a set of stimulus instructions which, when presented by said electrode array, produces a neural excitation pattern which approximates the spatio-temporal pattern associated with the travelling wave observed on the basilar membrane in an acoustically excited normally-hearing cochlea when stimulated with said sound signal.