Patent US 4,577,641

Disclosed is a process of fitting a hearing prosthesis to a deaf or severely hearing impaired patient. The prosthesis is connected to the patient, and a signal is then applied to the prosthesis across an audioband. The frequency response of the prosthesis is adjusted so that the patient detects a desired response to the signal. In one application the prosthesis may include a sound processor driving a transmitter, a transcutaneous receiver, and an implanted electrode. A constant amplitude signal is applied to the sound processor, and the frequency response of the sound processor is adjusted so that the patient detects a generally uniform response to the signal. Other signals can be applied, such as bursts of a sine wave or other periodic wave, and band-filtered noise can be employed with the band center frequency being swept either step-wise or continuously. The transmitter and receiver are first adjusted for normal operating coupling and then a constant amplitude continuous sinusoidal signal, for example, is applied. In a multiple channel system, the signal is applied sequentially to each channel. For each channel, the signal is varied in discrete frequency steps across an audio band, and the frequency response of the transmitter is adjusted so that the patient detects a generally uniform response. The dynamic range is identified at each such frequency step between a threshold level and a discomfort level to establish desired aided thresholds and discomfort levels.