| 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 143 | | .~.~ Sound intensifying or spreading element (381/156) {1} |
| FOR 144 | DD | .~.~.~> Mouthpiece (381/157) |