Microphone Types

Microphones are classified by the physical principle they use to convert sound into an electrical signal. Each type, or acoustic transducer, has characteristic strengths in sensitivity, robustness, frequency response and cost, which determine where it is used. Understanding the main families makes it easier to match a microphone to an application, from studio recording to telephones and measurement.

The dynamic, or moving-coil, microphone uses electromagnetic induction: a diaphragm drives a coil through a magnetic field, generating a voltage. It is hard-wearing, needs no power and copes with loud sources, which makes it a staple for live sound and instruments. The condenser, or capacitor, microphone works on a change of capacitance as sound moves a charged diaphragm relative to a fixed plate. It offers high sensitivity and a wide, detailed response, but needs a power supply. A common subtype is the electret condenser, whose diaphragm or backplate carries a permanently embedded charge, so it needs only a little power for its built-in amplifier; its small size and low cost make it ubiquitous in phones, laptops and consumer devices.

Other transducer types serve specialised roles. Piezoelectric microphones use a crystal or ceramic element that generates a voltage when mechanically stressed, and are rugged and well suited to contact pickups and high sound levels. Ribbon microphones, a variant of the dynamic principle, suspend a thin metal ribbon in a magnetic field for a smooth, natural response prized in recording. The choice among these types balances sound quality against durability, power requirements and price.

Frequently asked questions

What is an electret condenser microphone?

It is a condenser microphone whose diaphragm or backplate holds a permanent charge, so it needs only modest power for a built-in amplifier. Its small size and low cost make it very common.

How do dynamic and condenser microphones differ?

Dynamic types generate a signal by moving a coil in a magnetic field and need no power, while condenser types sense a change in capacitance, are more sensitive and require a supply.

Where are piezoelectric microphones used?

They use a crystal that produces voltage under stress, and being rugged and tolerant of high levels they suit contact pickups on instruments and other demanding applications.