On the basis of sensitivity
• Dynamic Microphone
• Condenser Microphone
• Electret Microphone
• Ribbon Microphone
On the basis of Direction
• Omnidirectional
• Unidirectional
• Bi-directional
Dynamic Microphones
• The dynamic microphone uses a wire coil and magnet to create the audio signal.
• The diaphragm is attached to the coil.
• When the diaphragm vibrates in response to incoming sound waves, the coil moves backwards and forwards past the magnet.
• This creates a current in the coil which is channelled from the microphone along wires.
• They are versatile and ideal for general-purpose use.
• They use a simple design with few moving parts.
• They are relatively sturdy and resilient to rough handling.
• Better suited to handling high volume levels, such as from certain musical instruments or amplifiers.
• They have no internal amplifier and do not require batteries or external power.
Condenser Microphone
• It has two plates with a voltage between them.
• One of these plates is made of very light material and acts as the diaphragm.
• The diaphragm vibrates when struck by sound waves, changing the distance between the two plates.
Electret Capsule Microphone
• The electret mic uses a special type of capacitor which has a permanent voltage built in during manufacture.
• This acts like a permanent magnet, this doesn't require any external power for operation.
• Though, good electret condenser mics usually include a pre-amplifier which does require power.
Ribbon Microphone
• Ribbon microphones have a very similar look to capacitor mics.
• Very popular with radio stations in the 1920s and 1930s .
• They are directional in nature, meaning that you must point them towards the sound you are hoping to pick up.
• Early models were very frail, but newer technology has helped their durability.
Directionality
Every microphone has a property known as directionality. This describes the microphone's sensitivity to sound from various directions. Some microphones pick up sound equally from all directions, others pick up sound only from one direction or a particular combination of directions.
Unidirectional Microphones
They pick up sound predominantly from one direction. They are more suitable for use in smaller studios. This includes cardioid and hypercardioid microphones.
a) Cardioid Microphones
• Cardioid means "heart-shaped", which is the type of pick-up pattern these mics use.
• Sound is picked up mostly from the front, but to a lesser extent the sides as well.
• Emphasising sound from the direction the mic is pointed while leaving some latitude for mic movement and ambient noise.
• The cardioid is a very versatile microphone, ideal for general use. Handheld mics are usually cardioid.
b) Hypercardioid Microphones
• This is exaggerated version of the cardioid pattern.
• It is very directional and eliminates most sound from the sides and rear.
• Due to their long thin design, they are often referred to as shotgun microphones.
• Isolating the sound from a subject or direction when there is a lot of ambient noise.
• Picking up sound from a subject at a distance.
• By removing all the ambient noise, unidirectional sound can sometimes be a little unnatural.
• It may help to add a discreet audio bed from another mic (i.e. constant background noise at a low level).
• You need to be careful to keep the sound consistent. If the mic doesn't stay pointed at the subject you will lose the audio.
• Shotguns can have an area of increased sensitivity directly to the rear.
Bi-directional Microphones
• It uses a figure-of-eight pattern and picks up sound equally from two opposite directions.
Eg: One possibility would be an interview with two people facing each other (with the mic between them).
Omnidirectional Microphones
• It captures ambient noise.
• Omni pattern mics tend to be the most technically accurate, but they may well pick up sounds not intended for them.
Omni sound is very general and unfocussed - if you are trying to capture sound from a particular subject or area it is likely to be overwhelmed by other noise.
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