The vast majority of speakers available on the market today are referred to as electrodynamic. All electrodynamic speakers share a fundamental aspect of operation: the reaction of a fixed magnetic field against a changing one. In most electrodynamic speakers, a voice coil, which is a single coiled length of wire wrapped around a cylinder called a former, produces the changing magnetic field when alternating current from the amplifier flows through it.

This current is an electrical representation of the sound that was produced by the musicians in the recording studio and causes the voice coil (and, therefore, the cone or dome attached to it) to react against the fixed magnetic field produced by the speaker's fixed magnet. A positive pulse should cause the cone to move outward, and a negative pulse should cause the cone to move inward. When the cone moves as a result of being propelled by the voice coil, it produces the changes in the air pressure of the listening environment that we perceive as sound.