Abstract: The cortical hearing aid is an instrument that produces the sensation of hearing by electrical stimulation of the neurons in the auditory cortex and/or auditory nerve trunk (eighth cranial nerve). The device employs an oscillator that generates a radio frequency carrier at a selected frequency within the range of 20 KHz to 60 KHz, with about 40 KHz producing optimum effectiveness. The RF carrier is modulated by the audio signal. An unbalanced bridge modulator is utilized to produce a modulated signal having substantially improved bandwidth and fidelity.

Abstract: Disclosed hearing aids have circuits that produce a suppressed-carrier modulated signal and they include an electrode to be applied to the head of the user for coupling the suppressed-carrier modulated signal to the user's auditory cortex.

Abstract: "Hearing" without involving the ear is realized by electrical conduction of the sound-representing signals on a carrier optimally in the frequency range of 15-60 kHz, from an electrode held against a person's head to the auditory cortex and possibly to the auditory nerve. This is here called a "cortical hearing aid". The ability of the person to recognize sounds with a cortical hearing aid is notably enhanced by introduction of significant distortion of the audio signals, especially low-order harmonics of the audio frequencies. The distortion acts as a substitute for distortion ordinarily occurring in the ear but disregarded in the hearing process.