×

HEARING AID WITH FREQUENCY-SELECTIVE AGC

  • US 3,571,529 A
  • Filed: 09/09/1968
  • Issued: 03/16/1971
  • Est. Priority Date: 09/09/1968
  • Status: Expired due to Term
First Claim
Patent Images

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.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×