US PATENT SUBCLASS 381 / FOR 141
.~.~ Including sound conducting tube (381/154)

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

FOR 127  DF  HEARING AIDS, ELECTRICAL (381/68) {15}
FOR 140  DD  .~ With acoustic wave modifying structure (381/153) {5}
FOR 141.~.~ Including sound conducting tube (381/154)