H
ELECTRICITY
H
ELECTRICITY
H04
ELECTRIC COMMUNICATION TECHNIQUE
H04
ELECTRIC COMMUNICATION TECHNIQUE
H04R
LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
H04R
LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
H04R1/00
Details of transducers,; loudspeakers or microphones
H04R1/00
Details of transducers,; loudspeakers or microphones
H04R1/08
Mouthpieces; Microphones;; Attachments therefor
H04R1/08
Mouthpieces; Microphones;; Attachments therefor