How audio and loudspeaker system works?

These are the basic units of audio communication system. Their basic structure is the same and they work in the opposite mechanism. When we speak the light membrane of the microphone known as diaphragm vibrates and the light case attached to it also vibrates. A coil is attached to the case which also vibrates. A magnet is placed near the coil which creates magnetic field. As the coil vibrates the magnetic flux associated with the coil changes. From Faraday's law of electromagnetic induction we can say the change in the magnetic flux creates induced emf and induced current in the coil. the coil is attached to a wire which passes through an amplifier an the other end of the wire is attached to the coil of the loudspeaker. The coil of the speaker is attached to a light case which in turn is attached to a light membrane. The induced current produced in the microphone side reaches the coil of the speaker and the presence of a magnet near that coil vibrates the coil and hence the membrane of the speaker producing the exact sound as caught by the microphone.

audio-loudspeaker

Basics type of microphones:

1.Dynamic microphones:

They are just ordinary microphones that use diaphragms, magnets, and coils. Condenser microphones work a slightly different way by using a diaphragm to move the metal plates of a capacitor (an electric-charge storing device) and generate a current that way. Most microphones are omnidirectional, which means they pick up sound equally well from any direction. If you're recording something like a TV news reporter in a noisy environment, or a rare bird tweeting in a distant hedgerow, you're better off using a unidirectional microphone that picks up sound from one specific direction. Microphones described as cardioid and hypercardioid pick up sounds in a kind of "heart-shaped" (that's what cardioid means) pattern, gathering more sound from one direction than another. As their name suggests, you can target shotgun microphones so they pick up sounds from a very specific location because they are highly directional. Wireless microphones use radio transmitters to send their signals to and from an amplifier or other audio equipment

2.condensed microphone

It is also called capacitance microphone.Diapharm acts as one plate whereas one metalic plate is placed forming capacitor.As we know

V=Q/C

 Where Q= charge holder by capacitor and 

C=capacitance.

As sound waves Strick on diaphragm it vibrates and changed the separation between them which changes capacitance between them .

C is inversely proportional to seperation between them .

As diaphragm moves inward C increase

As diaphragm moves outer C decrease .

These changes in voltage across terminal and produces electrical signal. 

3.ribbon microphone

In this microphone diaphragm i is replaced with ribbon ( mechanical mass made of aluminium ).it is less in weigh .it's working is same as dynamic type microphone. 

4.carbon microphone

It is used only in telephone due to its low SNR ratio. Its costs less than among others .it is omni directional but at 300 HZ.

Distortion is hight about 10% .

5.crystal microphone 

It  works on the piezoelectric effect. Crystal placed in mechanical pressure produces emf across it. As we speak sound waves strike on the crystal forming pressure on it and relatively emf is produced.

Direction- omnidirectional

Sensitivity-good 

SNR- 40db 

Distortion - less 

Application:

• Mobile communication
• Amateur communication
• Home recording system

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