When an electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the coil which thus becomes an electromagnet. The coil and the driver's magnetic system interact, generating a mechanical force which causes the coil, and so the attached cone, to move back and forth and so reproduce sound under the control of the applied electrical signal coming from the amplifier. The following is a description of the individual components of this type of loudspeaker.
For example, paper is light and typically well damped, but not stiff; metal can be made stiff and light, but it is not usually well damped; plastic can be light, but typically the stiffer it is made, the less well-damped it is. As a result, many cones are made of some sort of composite material. This can be a matrix of fibers including Kevlar or fiberglass, a layered or bonded sandwich construction, or simply a coating applied to stiffen or damp a cone.
