As per Ian Phillips’ message on one of the FB groups:
“One of the innovations used to enhance the realism of the US Army's huge Louisiana Maneuvers of 1941 was the deployment of vehicles fitted with powerful loud-speakers which broadcast amplified "battle" sound effects...explosions, gunfire, the roar of vehicles and the squeak and clatter of tank tracks etc.
Here we see one such vehicle...a Chevrolet panel van with triple speakers mounted on its roof.
(LIFE / Kessel)”
