| 381 / | HD | ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES |
| 150 | DF | ELECTRO-ACOUSTIC AUDIO TRANSDUCER {18} |
| 182 | DF | .~ Plural or compound reproducers {4} |
| 370 | DF | .~.~ Headphone {3} |
| 374 | | .~.~.~ Particular support structure {9} |
| 375 | DF | .~.~.~.~> And microphone |
| 376 | DF | .~.~.~.~> Headgear |
| 377 | DF | .~.~.~.~> Plural bands |
| 378 | DF | .~.~.~.~> Single band |
| 379 | DF | .~.~.~.~> adjustable |
| 380 | DF | .~.~.~.~> Ear insert or bone conduction |
| 381 | DF | .~.~.~.~> Hook over ear or spectacle |
| 382 | DF | .~.~.~.~> Sound conducting tube |
| 383 | DF | .~.~.~.~> Collapsible |