Prosthetic device for optimizing speech understanding through adjustable frequency spectrum responses

Claim 1

Prosthetic apparatus for providing compensatory amplification for aurally handicapped persons comprising: input circuit means for receiving signals to be amplified over selected first, second and third pass bands, an audio frequency preamplifier for receiving signals from said input circuit means for generating audio level frequency signals for driving a multiple channel filter network, a multiple-channel filter network comprising a first filter having a variable response at the low end of an audio speech band, a second filter having a variable response at the middle of the audio speech band, and a third filter having a variable response at the high end of the audio speech band, said first filter comprising means for adjustably controlling its gain and for adjustably setting its break frequency over a freguency range of approximately 0.8 kHz to 2.8 kHz to control the first filter's lowpass frequency responses, said second filter comprising means for providing mid-range variable bandpass frequency response adjustments with the channel gain, the "Q", and center frequency of said second filter being individually adjustable to control the amplitude of signals passed and the width and center frequency of its pass band, said third filter having a break frequency of approximately 1.4 kHz to 4.4 kHz and comprising means for adjustably controlling this break frequency and its gain to control said third filter's highpass frequency responses, adjustments means for individually controlling the filter gains, center frequency response of said second filter, the break frequency of said first and third filters, and the bandpass filter "Q" of the second filter to provide precise corrective hearing responses, means for coupling said audio level frequency signals to said filter network, a summation amplifier means coupled to the outputs of said filter network for combining signals from said first, second and third filters, a gain control coupled to the output signal of said summation means for generating a signal which is coupled to said input circuit means for compression of said signals over said filter network, and output circuit means coupled to said summation means for driving an audio frequency receiver.