How does loudspeaker work?

There are more than one type of loud speaker but the most common is a coil of wire suspended in a magnetic field. When alternating currents are passed through the wire, resulting vibrating magnetic fields push and pull against the permanent magnet. The coil is connected to a surface, usually conical, which moves back and forth because of this pushing and pulling causing sympathetic sound vibrations in the air adjacent to this surface which then move away as sound waves.