IPC Subgroup
H04R 21/02 Microphones
Introduced: September 1968
Last revised: January 2006
Full Title
Variable-resistance transducers > Microphones
Classification Context
- Section:
- ELECTRICITY
- Class:
- ELECTRIC COMMUNICATION TECHNIQUE
- Subclass:
- LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS