An implantable hearing unit is provided that includes an implantable microphone, a rechargeable power storage device and a speech signal processor. The hearing unit further includes a signal coupling device that is adapted for electrical interconnection to an implantable auditory stimulation device, which is operative to stimulate an auditory component of a patient. Such a stimulation device may include cochlear implants, brain stern stimulation systems, auditory nerve stimulation systems, and middle or inner ear transducer systems. The signal coupling device is operative to provide processed drive signals from the signal processor to the stimulation device as well provide power from the power storage device to operate the stimulation device. In one arrangement, the signal coupling device is a wireless coupling between first and second coils. In such an arrangement, the hearing unit may be utilized with an existing implanted stimulation device to make that device a fully implanted hearing system.