sound truck; loudspeaker van; propaganda vehicle
A vehicle equipped with loudspeakers, used for political campaigning, commercial advertising, or right-wing propaganda. Often associated with noisy street-level broadcasts.
During election season, sound trucks go around residential areas.
A right-wing group's propaganda vehicle was blaring a speech at high volume.
Before elections, sound trucks drive around town.
The candidate gave a speech from the sound truck.
The candidate's voice blared out from the sound truck.