An exemplary signal processing unit includes 1) a microphone configured to detect one or more acoustic signals, 2) processing circuitry configured to process the one or more acoustic signals, and 3) a port configured to receive one or more electrodes that are configured to be placed on an outer surface of the head of a patient and to detect one or more central auditory potentials. The processing circuitry may be further configured to process the detected central auditory potentials.
