US PATENT SUBCLASS 381 / 82
.~ Public address system

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

77  DF  ONE-WAY AUDIO SIGNAL PROGRAM DISTRIBUTION {4}
82.~ Public address system {3}
83  DF  .~.~> Feedback suppression
84  DF  .~.~> Spare amplifier substitution
85  DF  .~.~> Speaker or channel switching

DEFINITION

Classification: 381/82

Public address system:

(under subclass 77) Subject matter having an input transducer to convert sound into an electrical signal and an output transducer converting the electrical signal into sound so that the sound can be heard over a large area.

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75, for megaphones.

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369, Dynamic Information Storage or Retrieval,

1+, for public address systems combined with recording reproducers.