Microphones and their types 

We all are aware of the term “Microphone” or “Mic” or “Mike”  and we consider it to be a device that transmits audio signals to the computer or the speakers . But that is not enough when it comes to using one . With that note , we will discuss the topic “ Microphone” today, which is the 3rd and one of the key elements in any recording setup . 

Microphones comes in different shapes , sizes and the most important with different characteristics. Therefore , It is very important to understand different microphones and their qualities or characteristics to have a quality recording .

Basically, microphone is an acoustic-to-electric transducer or sensor that converts sound into electrical signals . Microphones are used in many applications such as telephone , hearing aids, public address system for concert hall and public events, motion picture production, live and recorded audio engineering, two ways radios, megaphones , radio and television broadcasting, and in computers for recording voice , speech recognition , VoIP, and for non acoustic purposes such as ultrasonic checking and knock sensors .

So, It is very important to know which microphone is to be used where to achieve the desired quality or sound we aim for before investing in one .

Varieties 

There are different varieties of microphone depending on their transducer principle , such as dynamic , condenser etc . and but heir directional characteristics .

Condenser Microphones

Dynamic Microphones 

Ribbon Microphones

Carbon Microphone

Piezoelectric Microphone

Condenser Microphones

The term condenser is actually obsolete but has stuck the name for this type of microphone, which uses a capacitor to convert acoustical energy into electrical energy . Condenser Microphones require power from a battery or external source which is +48 v DC and is commonly known as phantom power . Condenser Microphones audio signal is stronger signal than that from a dynamic microphone .

Condenser Mics are very sensitive to distant sounds and high frequencies and are generally used in studio recording situation . 

Dynamic Microphones

Dynamic Microphones are relatively cheaper than condensers and do not require an extra power from any kind of battery or external source . 

The Dynamic Microphone uses a wire coil and magnet to create the audio signal . The diaphragm is attached to the coil and when the diaphragm vibrates in response to incoming sound waves, the coil moves backwards and forwards past the magnet . Condenser Microphones are more handheld and can be used in different situation . These kind of microphones can be used in both studio as well as live concerts . They are considered to be all rounder microphones and are not much sensitive to high frequencies as condenser microphones .

Ribbon Microphones

A ribbon microphone, is a type of microphone that uses a thin aluminium, duraluminum or nano film of electrically conductive ribbon places between the poles of a magnet to produce voltage by electromagnetic induction .

They are beautifully engineered and are most likely suitable for trumpets or other brass instruments . Generally ribbon microphones sound sweet and smooth but need a preamp with clear high gain .

They are fragile in nature and are more suitable to use inside a studio environment .

Carbon Microphones

Carbon Microphones also known as button microphone is a type of microphone that converts sound to an electrical audio signal . It consists of two metal plates separated by granules of carbon. Carbon microphones were once known for their high output level performance, low impedance and reasonably low cost . One of the major drawbacks of these was its low quality of sound reproduction and limited frequency response as well as high hiss noise .

Crystal Microphones/ Piezoelectric Microphones

Crystals which demonstrate the piezoelectric effect produce voltages when they are deformed .The crystal microphone uses thin strip of piezoelectric material attached to diaphragm . The two sides of the crystal acquire opposite charges when the crystal is deflected by the diaphragm. They are durable and cheap, and have relatively large electrical output ; which is the reason why they are used in telephones and portable sound systems . They are not adequate for quality recording .

Polar Pattern or Directionality 

A microphones directionality or polar pattern defines how sensitive it is to sounds arriving at different angles about its central axis .

Below are the different polar patterns of microphones :

Omnidirectional
Bidirectional/ Figure of 8
Unidirectional
Cardioid
Subcardioid
Hypercardiod
Supercardiod
Shotgun

Omnidirectional 

Omnidirectional microphones are the microphones that pick up sound with equal gain from all directions of the microphone . Whether a user speaks into to the microphone from any direction , the mic will record the signals all with equal gain . The is opposite to unidirectional microphones, which pick up sound with high sensitivity only from a specific side .

Bidirectional/ Figure of 8

Bidirectional polar pattern is equally sensitive on the two opposite faces of the mic that correspond to the front and the rear of the diaphragm, while rejecting sounds from the sides .

Unidirectional

Unidirectional Microphones are those pics which are sensitive to predominantly from a single direction . Thus if a user is speaking into the microphone , he must speak to the correct side,normally called the voice side .

Cardioid

Cardio patterns mostly are sensitive to the sound at the front and least at from the back . Their unidirectional pattern are affective for sound isolation of unwanted ambient noise and resistance to feedback when compared to omnidirectional microphones .

Sub cardioid 

Subcarioid is a obscure polar-pattern and many refer it as ‘wide cardioid’ . The directionality is quite close to omni- but not quite- resulting in a very natural, open sound suitable for performances with low stage volume where a more organic sound is desirable . Sub cardioid polar patterns are also much less prone to the proximity effect  but more susceptible to feedback . 

Hyper cardioid

Hypercardioid patterns are similar to cardioid patterns in primarily sensitive in the front of the microphone .They differ, however, in that the point of least sensitive is at 150 - 160 and 200 - 210 degree positions ( as opposed to directly behind the microphone in a cardioid pattern ).

Hypercardioid miss are thus considered even more directional than cardioid microphones because they have less sensitivity at their sides and only slightly more directly behind .

Supercardioid 

Super cardioid microphones offer a narrower pickup than cardioids and a greater rejection of ambient sound . However, they also pick up a small amount of sound from directly behind .

They fall off quite quickly and it is about -10db at 90 degrees . The angle of maximum rejection is 120 degrees .

Super cardioid are highly suited to very loud stage environments as they are very directional with high gain before feedback .

Line and gradient / Shotgun 

Line and gradient microphones use a complex design that makes their polar pattern highly directional . They capsule is placed behind an interface tube with small slits along the side . The tube eliminates sound from the sides due to phase cancellation . The longer the interference tube , the tighter the polar pattern , making the microphone better at rejecting sound from the side and more focused in the direction it is pointing .

For more information about Microphones, check the link below 

https://en.wikipedia.org/wiki/Microphone