Special purpose hearing aid
United States Patent 3394226
US Patent References:
Apparatus for reducing noise in microphone circuits
- - 2449971
Noise reduction system
- - 2972018
Method of improving intelligence under random noise interference
- - 2866848
Automatic sound control
- - 3098121
2-wire-4-wire telephone converter for use on unstable 4-wire circuits
- - 3174100
Apparatus for reducing noise in microphone circuits
- - 2449971
Noise reduction system
- - 2972018
Method of improving intelligence under random noise interference
- - 2866848
Automatic sound control
- - 3098121
2-wire-4-wire telephone converter for use on unstable 4-wire circuits
- - 3174100
Inventors:
Andrews Jr., Daniel E.
Publication Date:
07/23/1968
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Primary Class:
Other Classes:
381/320, 381/94.300, 381/317
International Classes:
H04R25/00