An exemplary signal processing unit includes a plurality of filters configured to divide an audio signal into a plurality of analysis channels, one or more detection stages configured to detect an energy level within each of said analysis channels, a selection stage configured to select one or more of said analysis channels for presentation to a patient, a synthesizer stage configured to synthesize said selected analysis channels, and a mapping stage configured to map said selected analysis channels to a number of stimulation channels within an implantable cochlear stimulator, wherein a total number of said analysis channels is greater than a total number of said stimulation channels.