1. MICROPHONES Secondary transducer:
Are the transducers that converts variation in sound pr into analogous electrical signals
Microphones generally employ a thin diaphragm which converts pr into displacement
Displacement is subsequently converted into suitable electrical signal by employing a secondary transducer
Secondary transducer:
Capacitor type
Piezoelectrical crystal type
Electrodynamic type
Carbon granual type

2. PIEZO-ELECTRIC CRYSTAL MICROPHONE

3. ELECTROMAGNETIC MICROPHONE

4. CAPACITIVE MICROPHONE