Digital Audio Fundamentals

The three main types of microphones used in onstage and studio environments are dynamic, condenser, and ribbon microphones. There are also many other types that have more specific uses.

• Carbon microphone - also called "button microphones" and commonly found in old landline telephones, these microphones uses thin metal plates and granulated carbon to transmit audio signals into electricity.
• Piezoelectric microphone - also called crystal or piezo microphones, these use piezoelectricity - where some materials produce voltage when pressure is subjected - to convert audio frequencies into electric signals. For example, potassium sodium tartrate is a piezoelectric crystal that works as a transducer, both as a microphone and as a slimline loudspeaker component.
• Fibre-optic microphone - fibre-optic microphones convert acoustic waves into electrical signals by sensing changes in light intensity, instead of sensing changes in capacitance or magnetic fields as with conventional microphones. These microphones are used in areas where electrical or magnetic interference could cause issues, such as inside industrial turbines or in magnetic resonance imaging (MRI) environments.
• Laser microphone - most often used in surveillence contexts, a laser microphone uses a laser beam to detect audio vibrations from reflective surfaces such as windows, which are then translated into an audio signal.
• Lavalier microphones - lavalier microphones (also known as a lav, lapel mic, clip mic, body mic, collar mic, neck mic or personal mic) are small microphone used for television, theatre, and public speaking environments to allow hands-free operation.
• Shotgun microphones - Shotgun microphones are highly directional, which means that they can pick up sound from a specific direction while filtering out background noise.  They are frequently used in film and TV production.
• Speaker - the basic principles by which dynamic microphones operate are the same for speakers - a coil of wire in a permanent magnetic field. Large speakers can be used to record the very low frequencies of bass drums, bass guitar cabinets, and other instruments with a lot of low-end power and energy.

Thompson, D. M. (2005). Understanding audio. Berklee Press.

Polar pattern illustrations from: https://blog.andertons.co.uk/learn/microphone-polar-patterns-explained.

The term "polar pattern" (sometimes called "pickup pattern") refers to the directionality of a microphone. These patterns help identify the optimum sensitivity range of a particular microphone for capturing sound from different angles or directions.

Certain polar patterns are better for vocals, different recording scenarios, or capturing specific instruments. For example, a unidirectional microphone is great for recording vocals (i.e. a sound source coming from a specific direction) but not so much for capturing a whole choir. Similarly, an omnidirectional microphone wouldn't be used on a drum kit, especially if you require separation between the various pieces of the kit.

Cardioid/unidirectional pattern:

A cardioid polar pattern means that the microphone picks up sound from the direction you point it in and cancels any sound coming from behind.

Bidirectional:

A bidirectional polar pattern captures an equal amount of sound from the front and back of the mic, and doesn’t capture any sound from the sides. Mics using this pattern boast the highest side rejection of every polar pattern.

Omnidirectional:

Omnidirectional microphones have equal response at all angles. Its coverage or pickup angle is a full 360 degrees, which means they are good for capturing natural and opens sounds like acoustic guitars, although they are more sensitive to the ambience of different spaces.

The most common connectors used by microphones are:

• Male XLR connector (three-pin plug) on professional microphones.
• 1⁄4 inch phone connector on less expensive musician's microphones, using an unbalanced 1⁄4 in (6.35 mm) TS (tip and sleeve) phone connector.
• 3.5 mm (sometimes referred to as 1⁄8 inch mini) TRS (tip, ring and sleeve) stereo (also available as TS mono) mini phone plug on prosumer camera, recorder and computer microphones.
• USB allows direct connection to PCs. Electronics in these microphones powered over the USB connection performs preamplification and ADC before the digital audio data is transferred via the USB interface.
• Some microphones use other connectors, such as a 5-pin XLR, or mini XLR for connection to portable equipment. Some lavalier microphones use a proprietary connector for connection to a wireless transmitter, such as a radio pack.