Electric Siren
Mechanical sirens blow air through a slotted disk or rotor. The cyclic waves of air pressure are the physical form of sound. In many sirens, a centrifugal blower and rotor are integrated into a single piece of material, spun by an electric motor.
An electric motor siren is a type of alarm or warning device that uses an electric motor to produce a loud, high-pitched sound. It is often used in emergencies to alert people to danger. Electric motor sirens are also sometimes used in non-emergency situations.
Electronic sirens are high efficiency loudspeakers, with specialized amplifiers and tone generation. They usually imitate the sounds of mechanical sirens in order to be recognizable as sirens.
The sirens are activated for a 3 minute rotation to alert those outdoors of any outdoor emergencies approaching. The sirens auto-activate when National Weather Service issues a tornado warning or a severe thunderstorm warning with hail exceeding 1.75″ and/or wind exceeding 70 mph.