A loudspeaker is a device designed to reproduce sounds. It takes an electrical signal and coverts it in to sound wave vibrations in the air.
The loudspeaker does this through the power of electromagnets, the electrical signal that travels to the loudspeaker is an ‘alternating current’, it turns on and off. This, in turn, turns the electromagnet on and off, which acts to pull the speaker cone back and forth. The speed at which the current alternates will directly affect the speed at which the speaker cone moves and the sound wave produced.