the hearing aid includes n electrodes for being implanted in the cochlea at n different points chosen to allow identification by the brain of multiple frequency bands of a sound spectrum . a microphone receives the sound spectrum and outputs a sound signal . the instantaneous energy in the frequency bands in the sound signal is measured . the electrodes are operated cyclically as a function of the energy measured in the frequency bands and in an order determined in accordance with a time distribution of the energy in the frequency bands .