The document summarizes the history and types of microphones. It describes how the first microphone was invented in 1876 and key developments like the ribbon microphone in 1931 and electric microphone in 1964. It then explains how microphones work by transforming sound waves into electrical signals. The main types of microphones are described - dynamic, condenser, ribbon, carbon, crystal - along with their characteristics. Polar patterns like omni-directional, bi-directional and cardioid are also covered. The document concludes by discussing the purpose of different microphones and their appropriate uses.

1. Unit 17 Audio Production Processes Assignment 3
Microphone types and characteristics
History of the microphone;
1876 - The year in which the first microphone was invented using an early
telephone device, the inventor Emile Berliner had created by using the bell
company telephones, he was looking for different way to improve the
telephone and created a new type of transmitter which allowed you to increase
the volume of speech when spoken into.
“A loose contact transmitter”
1878 – The later development of microphones after Emile Berliner’s invention, David Edward Hughes
created the first carbon microphone; along with many other inventors who tried to expand on the
original discovery of microphone technology.
1931 - As radio broadcasts were becoming more popular and the carbon microphone did not fit the
needs as well as would be liked, the first ribbon microphone was introduced, the RCA PB-31
designed by Harry F Olson.
1964 – James West & Gerhard Sessler released the electric microphone, the most commonly used
and reliable microphone, used a lot in current times because of the device being more portable ,
still with a high precision microphone.
How a microphone works –
Microphone – “an instrument capable of transforming sound waves into changes in electric currents
or voltage, used in recording or transmitting sound.”
1. When a microphone is spoken into the sound waves which are made by your voice travel
towards the microphone using the vibrations in the air.
2. “Inside the microphone, the diaphragm (much smaller than you would find in a loudspeaker
and usually made of very thin plastic moves back and forth when the sound waves hit it.”
3. The coil inside the microphone moves backwards and forwards due to the vibrations from
the sound waves.
4. “The permanent magnet produces a magnetic field that cuts through the coil. As the coil
moves back and forth through the magnetic field, an electric current flows through it.”

2. Unit 17 Audio Production Processes Assignment 3
5. The current which flows through the microphone due to the above actions, the original
sound waves are turned into electricity, due to this happening it is possible to amplify the
electric current and then play out of a loudspeaker.
Types of microphones;
Dynamic microphone – This style of microphone uses vibrations of the sound waves. The sound
waves travel through the microphone which has a metallic coil with a magnetic field around it
caused by a magnet, this allows the current to flow.
Electret/condenser microphone - These two types of microphones are both similar in the way that
a collected charge of electricity is created between two pieces of metal. “Condenser micsmake use of
a thin piece of metal foil that is stretched above another piece of metal, as the foil moves it changes
the capacitance of the system. This can be detected and turned into a current.” Whereas an Electret
microphone keeps the back piece of metal with a constant flow of electricity flowing through it.
Electret microphones are used in mobile phones because they can be mad extremely small and have
a good response to frequencies.

3. Unit 17 Audio Production Processes Assignment 3
Ribbon – The type of microphones are similar to dynamic microphones, using air particle movement
created by the sound waves when they reach the aluminium ribbons which are surrounded by a
magnetic diaphragm, a fixed ribbon unlike the dynamic which is allowed to vibrate, the downside of
this is that the ribbon microphone produces a lower electrical signal so and output transformer is
often used to boost the power.
Carbon - The first microphone design, still used to this day but not for recording music or sounds
with high frequency’s. These types of microphones worked well when the were invented due to
being durable and cheap, so all radio stations could afford them, the same design was used in
phones. Sound waves when they hit the microphone reach carbon particles, which vibrate creating a
current.

4. Unit 17 Audio Production Processes Assignment 3
Crystal - “Sound vibrates the diaphragm that moves the armature that bends the crystal. Small
copper foil strips attached to the Rochelle salt crystal transmit the electricity out to the amplifier
connector.”
Lavalier - A microphone used by reporters, singers and many more circumstances, the type of
microphone used in it is either a dynamic or electret because the microphone can be reduced to
such a small size making it easy to use.
Rifle – This type of microphone is for recording something far away, undercover surveillance etc.,
has to be a high frequency microphone so that it picks up conversation from a long distance, either
placed on the end of a camera or on a beam.
Boom – A boom microphone is used for television programs, for recording conversation from a short
distance , usually placed on a rod and put in the air out of shot on camera.
Radio – This is a wireless microphone, used a lot in day to day life, by singers on stage, radio
presenters, most things broadcasted live on television or too a audience these are used, it works by
a wireless channel transmitter fitted to both the microphone and the receiver, when set to the same
channel what is said into the input (the microphone) is transferred to the output (the receiver).
Boundary microphone (PZM) – A boundary microphone is used in many situations, in a office when
communicating between offices, on the stage of a theatre so that dialogue can be picked up and put
forward to the crowd. A high frequency microphone is used inside the design so that sounds from a
distance can be picked up, used for its amplification of acoustics.

5. Unit 17 Audio Production Processes Assignment 3
Polar patterns;
Omni – a commonly used microphone design, able to pick up sound from a 360 degree radius and
not alter the definition of the sound taken in.
Bi-Directional – this polar pattern only picks up sound waves from the front and the back of the
microphone, all sounds coming in from the sides won’t be heard or will be distorted, cannot be used
when recording a lot of things has to be for a select cause e.g. Recording instruments.
Cardioid – this polar pattern is used for live broadcasting or for singer’s performances on stage
because the sound waves can only be picked up from the front, so the audience’s noise does not
affect the quality of the sound coming from the microphone.
Hyper-Cardioid – much like the cardioid but due to having the small back sound pickup it produces a
better sound because it has the all-round frequency response.
Shotgun – “A "shotgun" mic carries these techniques to extremes by mounting the diaphragm in the
middle of a pipe. The shotgun is extremely sensitive along the main axis, but possesses pronounced
extra lobes which vary drastically with frequency. In fact, the frequency response of this mic is so
bad it is usually electronically restricted to the voice range, where it is used to record dialogue for
film and video.”
Purpose of Different Microphones;
It is important that when planning to record a subject or recording a subject that you have the
correct microphone which is suitable for the job, depending on the Omni directional patterns which
pick up sounds from different parts of the circumference of the microphone which is more suitable
for recording. In a studio the main types of microphones are Dynamic & Condenser.
Dynamic – This type of microphone is used when recording particularly instruments and vocals
because the microphones can withstand high-pressure levels, useful when recording with loud guitar
amps in the background. The problem with them is that the sound achieved is not as clear as from a
condenser.
Condenser – This is the most commonly found microphones, chosen for studio work due to it ability
too produce a louder sound than other microphones. A more delicate expensive microphone so has
to be taken care of, dynamics are used instead because of there rugged ness. When looking into
buying condenser’s you have either large diaphragm microphones which is for recording deeper
pitch sounds with some sounds causing distortion because of theresensitivity and small diaphragm

6. Unit 17 Audio Production Processes Assignment 3
microphones have the best response to sound converting the sounds quickly also the microphone
isn’t as sensitive to some sounds so the sound coming from the output isn’t distorted, very clear.

7. Unit 17 Audio Production Processes Assignment 3
References –
Microphone definition - http://dictionary.reference.com/browse/microphone
Polar patterns - http://artsites.ucsc.edu/EMS/Music/tech_background/TE-20/teces_20.html
How a microphone works - http://www.explainthatstuff.com/microphones.html
2 & 4, how a microphone works - http://www.explainthatstuff.com/microphones.html
Shot gun polar pattern - http://artsites.ucsc.edu/EMS/Music/tech_background/TE-
20/teces_20.html
Dynamic & Condenser microphone picture -
http://artsites.ucsc.edu/EMS/Music/tech_background/TE-20/teces_20.html
Carbon Microphone diagram -
http://upload.wikimedia.org/wikipedia/en/4/4e/Carbon_microphone.svg
Condenser microphone definition - http://www.jt30.com/jt30page/howmicswork.html
Ribbon Microphone diagram -
http://www.ustudy.in/sites/default/files/images/ribbon%20microphone.jpg
Crystal microphone diagram & description - http://www.jt30.com/jt30page/howmicswork.html