US PATENT SUBCLASS 340 / 286.03
.~.~ Speaking tube including circuit

Current as of: June, 1999
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340 /   HD   COMMUNICATIONS: ELECTRICAL

286.01  DF  SYSTEMS {24}
286.02  DF  .~ Network signaling {1}
286.03.~.~ Speaking tube including circuit

DEFINITION

Classification: 340/286.03

Speaking tube including circuit:

(under subclass 286.02) Subject matter in which a tube-shaped device mechanically transmits and/or amplifies sound in combination with a diverse electrical circuit.

SEE OR SEARCH CLASS

181, Acoustics,

.5, for a speaking tube, per se; e.g., without diverse circuitry.