US PATENT SUBCLASS 381 / FOR 140
.~ With acoustic wave modifying structure (381/153)


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381 /   HD   ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES

FOR 127  DF  HEARING AIDS, ELECTRICAL (381/68) {15}
FOR 140.~ With acoustic wave modifying structure (381/153) {5}
FOR 141  DD  .~.~> Including sound conducting tube (381/154)
FOR 142  DD  .~.~> Directional (381/155)
FOR 143  DD  .~.~> Sound intensifying or spreading element (381/156) {1}
FOR 145  DD  .~.~> Absorbing or attenuating element (e.g., baffle, obstruction, damping) (381/158)
FOR 146  DD  .~.~> Enclosure or resonant cavity (381/159)