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
1/00
Details of transducers,; loudspeakers or microphones
1/00
Details of transducers,; loudspeakers or microphones
H04R1/20
Arrangements for obtaining desired frequency or directional characteristics
H04R1/20
Arrangements for obtaining desired frequency or directional characteristics
H04R1/22
for obtaining desired frequency characteristic only
H04R1/22
for obtaining desired frequency characteristic only