Speakers

Speakers are devices that convert electrical signals into sound. They are used on almost every electrical device that makes sound: cell phones, computers, and televisions.

Mechanisms
The most common method of converting electricity to sound is to pass the incoming electricity through an inductor, known as a voice coil, to set up an electromagnetic field. The voice coil is suspended near a magnet, so it is attracted to or repelled from the magnet, depending on the electricity's flow direction. The voice coil moves in approximate motion to the incoming voltage. When the electrical signal imitates the vibrations in the air caused by an original sound, the speaker moves in a similar way and reproduces the sound.