HEARING AID WITH FREQUENCY-SELECTIVE AGC
First Claim
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1. A wearable electronic hearing aid comprising:
- a microphone for receiving ambient sound waves and converting them to audiofrequency electrical signals;
a transistorized audio amplifier coupled to said microphone for amplifying said electrical signals;
an electromechanical transducer coupled to said amplifier for converting said amplified electrical signals to intelligible audio information at a power level higher than that of said ambient sound waves, said microphone, audio amplifier and transducer being effective to produce amplification of sound waves of frequencies within a predetermined overall audible frequency response range;
an automatic gain control loop coupled to said audio amplifier and responsive to electrical signals of an amplitude greater than a predetermined threshold for developing a control effect proportional to said amplitude and for utilizing said control effect to control the gain of said audio amplifier for signal amplitudes above said threshold; and
frequency-selective means included in said automatic gain control loop comprising;
a. a pair of series-connected capacitors interposed in said loop;
b. a third capacitor adapted to be connected between said capacitor pair and a plane of reference potentiAl;
c. and switch means connected to said capacitors and having a first position for selectively shorting one of said capacitor pair, a second position for selectively connecting said third capacitor to said reference potential plane, and a third position for both shorting one of said capacitor pair and connecting said third capacitor to said reference potential plane, thereby providing low-frequency AGC, high-frequency AGC, and all-frequency AGC as desired.
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Abstract
A hearing aid wherein automatic gain control (AGC) is provided by using an AGC system incorporating a user-variable, frequencyselective amplifier to simultaneously establish an adequate range of AGC control voltage and enable selection of he frequencies to which the AGC system responds. The control circuit comprises a frequency-selective network, an amplifier, and a rectifier connected in cascade to limit the gain of the hearing aid only in response to received audio sound waves of frequencies within a selected portion of the frequency response range of the hearing aid.
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1 Claim
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1. A wearable electronic hearing aid comprising:
- a microphone for receiving ambient sound waves and converting them to audiofrequency electrical signals;
a transistorized audio amplifier coupled to said microphone for amplifying said electrical signals;
an electromechanical transducer coupled to said amplifier for converting said amplified electrical signals to intelligible audio information at a power level higher than that of said ambient sound waves, said microphone, audio amplifier and transducer being effective to produce amplification of sound waves of frequencies within a predetermined overall audible frequency response range;
an automatic gain control loop coupled to said audio amplifier and responsive to electrical signals of an amplitude greater than a predetermined threshold for developing a control effect proportional to said amplitude and for utilizing said control effect to control the gain of said audio amplifier for signal amplitudes above said threshold; and
frequency-selective means included in said automatic gain control loop comprising;
a. a pair of series-connected capacitors interposed in said loop;
b. a third capacitor adapted to be connected between said capacitor pair and a plane of reference potentiAl;
c. and switch means connected to said capacitors and having a first position for selectively shorting one of said capacitor pair, a second position for selectively connecting said third capacitor to said reference potential plane, and a third position for both shorting one of said capacitor pair and connecting said third capacitor to said reference potential plane, thereby providing low-frequency AGC, high-frequency AGC, and all-frequency AGC as desired.
- a microphone for receiving ambient sound waves and converting them to audiofrequency electrical signals;
Specification