Music Philately- Microphones on Stamps

Most microphones today use electromagnetic induction (dynamic microphone), cap
acitance change (condenser microphone), piezoelectric generation, or light modulation to produce an electrical voltage signal from mechanical vibration.
The sensitive transducer element of a microphone is called its element or capsule. A complete microphone also includes a housing, some means of bringing the signal from the element to other equipment, and often an electronic circuit t
o adapt the output of the capsule to the equipment being driven. Microphones are referred to by their transducer principle, such as condenser, dynamic, etc., and by their directional characteristics. Sometimes other characteristics such as diaphragm size, intended use or orientation of the principal sound input to the principal axis (end- or side-address) of the microphone are used to describe the microphone.

