A SOFTWARE MODEL OF THE COCHLEAR

To describe the inner ear functions, and in particular the frequency d ispersion occurring there, cochlear models have a great number of stag es in a lowpass filter chain. The ''Silicon Cochlea'' designed by Lyon and Mead consists, for instance, of a chain of 480 lowpass filter sta ges and frequency channels respectively; the model designed by J. Kate s has 112 stages. Present cochlear implant systems have a number of Fr equency channels, typically 8, 16 or 22. To compare the behaviour of t hese cochlear implant systems with cochlear models, and finally to int egrate such a model into the cochlear implant, a radical reduction of the number of frequency channels is necessary to meet the technical co nstraints of the implant system. Otherwise a suitable adaption of the filter stages to preserve the functional capabilities of the whole mod el is required. This work describes a cochlear model with 16 frequency channels. Models of the outer ear and the middle ear are presented, a dditionally, to cover the complete path of natural signal transmission . The connected models of outer, middle and inner ear show a behaviour which is in good relation to results of measurements at the natural h earing nerve, so that they can be used for the tasks mentioned above.