Sound truck
Encyclopedia
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
s, typically used to play loud political or commercial messages, but are also used in evacuation
Emergency evacuation
Emergency evacuation is the immediate and rapid movement of people away from the threat or actual occurrence of a hazard. Examples range from the small scale evacuation of a building due to a bomb threat or fire to the large scale evacuation of a district because of a flood, bombardment or...
s. The use of sound trucks for advertising is illegal in many jurisdictions.
See Kovacs v. Cooper, 336 U.S. 77 (1949)
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