US PATENT SUBCLASS 381 / 181
.~.~.~.~ Differential

Current as of: June, 1999
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381 /   HD   ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES

150  DF  ELECTRO-ACOUSTIC AUDIO TRANSDUCER {18}
369  DF  .~ Microphone capsule only {10}
179  DF  .~.~ Resistive {1}
180  DF  .~.~.~ Granular or carbon {1}
181.~.~.~.~ Differential

DEFINITION

Classification: 381/181

Differential:

(under subclass 180) Subject matter having two sound responsive resistance elements one positioned on either side of a central diaphragm.