381 / | HD | ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES |
150 | DF | ELECTRO-ACOUSTIC AUDIO TRANSDUCER {18} |
182 | .~ Plural or compound reproducers {4} | |
370 | DF | .~.~> Headphone {3} |
184 | DF | .~.~> Different types of diaphragms |
185 | DF | .~.~> Having common voice coil |
186 | DF | .~.~> Plural diaphragms |