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
H04R29/00
Monitoring arrangements; Testing arrangements
H04R29/00
Monitoring arrangements; Testing arrangements