implant the audio signal 11 is processed according to the so called continuous interleaved sampling strategy according to this strategy the audio signal 11 is first filtered by a number of different band pass filters covering the speech frequency range this number corresponds to the number of electrode channels an electrode channel is a combination of electrode surfaces in the cochlea in this way the tonotopic organisation place frequency coding of the cochlea is simulated next the envelope of the filtered audio signal in each channel is determined typically by using a rectifier and a low pass filter this envelope is compressed and modulated with an electric current pulse train in each channel according to several models which describe the peripheral auditory processing of normal hearing the neural activity at the onset of a sound stimulus is much higher than the activity after the onset the more suddenly the intensity of the stimulus increases the higher this activity will be the duration of this so called short term adaptation is in the order of magnitude of 10 ms it is assumed that the origin of the adaptation effect is at the inner hair cell auditory nerve synapse since a cochlear implant bypasses the haircells no adaptation effect is seen in the nerve fiber 39 s response to electrical stimulation fig2 shows a block diagram of a circuit for transforming an audio signal into an output signal according to the present invention in which transformation the short term adaptation effect is incorporated a number of these circuits arranged in parallel may be included in the hearing instrument according to the invention the audio signal 11 is band pass filtered in a filter 20 in order to simulate the tonotopic organisation of the cochlea by means of a rectifier.