In this era of digitization microphone (also called as mic or mike) has taken a huge part, without this so many things can’t be possible. In day to day life we use microphones in so many places and for so many things, without this a phone call over telephone or over mobile phone is not even possible. By using a microphone we can record our voice and save it, and that can be transferable to any place in the world. So mic made it possible to send our voice from one corner of the world to another corner, It also made it possible to hear a voice which was recorded hundreds year before by our ancestors or its possible to preserve and play someone’s voice after thousands year also.
What is a microphone?
A microphone is an instrument that converts sound to electrical signal. So basically it’s a transducer that converts one form of energy to another form. Microphone takes sound wave or the variation in pressure of air as input and gives electrical signals as an output.
There are different types of microphone and they use different techniques to convert sound to electric signals. The most common microphones are dynamic microphone, condenser microphone, and the piezoelectric microphone. Generally microphones are connected to an Amplifier before it gets recorded. Because the electric signals generated by a microphone is very small and measured in millivolts. Amplifiers modify the sound quality as per the requirement.
How does mic work?
There are many techniques by which mic converts sound to electric signals. We will discuss here two commonly used techniques used in dynamic and condenser microphones.
In this type of microphones are commonly used simple and versatile microphones. It use electromagnet principle, a coil is suspended in a magnetic field which when moves there inside the magnetic field, electric current generate in this.
Here there is a soft and very flexible diaphragm mounted at the front end of the microphone. And the coil is fixed with the diaphragm. A permanent magnet is place at the center part of the coil which produces enough magnetic fields around the coil. When sound waves come and strike the flexible diaphragm, the diaphragm starts vibrating back and forth. The coil also moves with the diaphragm as it is fixed with it. In a result an electrical current is induced in it and carried out to the amplifier. It is exactly the reverse mechanism of a loudspeaker. To know how a loudspeaker works and how it’s working principle is reverse to a microphone go to our article on Loudspeaker.
Its working principle is slightly different from the dynamic microphone. Condenser means capacitor which is a device consists of two plates separated and insulated from each other and equally charged with opposite charged. Capacitor is used to store energy charge and energy in electrostatic from. In condenser Microphone a capacitor is used. To provide required potential between two plates of the capacitor, one DC battery of 12-48V is connected to the capacitor and the battery is present inside the microphone.
Among two plates of the capacitor, one is very soft and flexible, used as a diaphragm. Another plate is strong and fixed in parallel with the other one at a slight distance. When sound waves come and strike with the diaphragm, the flexible plate start vibrating. Due to this back and forth move of one plate, the distance between two plates start increasing and decreasing. When the gap decrease, the capacitance between two plates increase, electrostatic energy increase, as a result charge current occurs. When the gap between two plates increase, capacitance decrease, and discharge current occurs, i.e the stored charge starts flowing out. This way a fare electric signal can be noted from a condenser Microphone when sound waves strike it.
Condenser mic is more sensitive than dynamic mic. It can note a sound of flat frequency also that a dynamic microphone fails to detect.
Polar pattern of a mic
Polar pattern of a microphone is the directional property. It describes how sensitive a microphone is to the sound arriving to it from different directions. Mainly it is of three types according to its directional property.
- Unidirectional: Unidirectional mic are sensitive to the sound coming from one direction. Generally the sounds coming from the front end of it can be noted by these kinds of mic. Sounds coming from the back end side or from any angle can be either unclear or ignored by these kinds of mics.
- Bidirectional: This kind of mic are sensitive to the sounds coming from either the front end or the back end of the microphones. Sound coming from the sided of the mic can’t be noted by bidirectional microphones. Principle says this mic response to the change in pressure between its front end and back end. As the sound coming from side of a mic reaches both back and front end equally, its not sensitive to those sounds.
- Omnidirectional: This kind of mic is highly efficient. It is sensitive to the sound coming from any direction or from all three dimensions. Generally very small diameter of this kind of mic makes it omnidirectional. Due to its small size, it can accept the sound frequency less or more, coming to it from any directions.
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