A mechanical siren uses a rotor and stator to "chop" an air stream, which is forced through the siren by radial vanes in the spinning rotor，

Electronic sirens produce their sound in a fashion that is fundamentally different from electromechanical sirens. Instead of a motor-driven rotor spinning inside a stator, electronic sirens consist of an electronic tone generator, a high-power amplifier, and a horn loudspeaker typically incorporating one or a multiple of compression drivers.