A speaker is a device that converts an electrical signal into sound or acoustical energy. In most speaker designs, sound waves emanate from the air pressure fluctuations created by the back and forth movement of a coil. Speakers typically consist of a voice coil, magnet, and cone.

The cone of a speaker provides the main moving mass, and it greatly determines the sound output. The surface area of a speaker is a factor of the size of the cone, and it determines the amount of air that this audio device can move. The voice coil is the field generating part of a speaker, and it is suspended in position. The movement of the cone is a result of the interaction between the standing magnetic field created by the magnet and the coil-generated magnetic field.

When the speaker’s coil is stimulated by an electric current it produces a magnetic field of alternating polarities. The permanent magnet correspondingly attracts and repels this alternating field, which causes the movements of the cone (usually attached to the coil). The sound from a speaker is a result of this movement of the cone.

Specialized speakers are called drivers, and they traditionally come in three types: tweeters, midrange, and woofers. Tweeters are specifically designed to produce high frequencies while woofers specialize in low frequencies. Midrange drivers handle midrange frequencies.