381 / | HD | ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES |
FOR 127 | DF | HEARING AIDS, ELECTRICAL (381/68) {15} |
FOR 138 | DF | .~ Having enclosure or housing (381/138) {1} |
FOR 139 | .~.~ With loudspeaker (e.g., baffle, spatial orientation, etc.) (381/90) |