Show ears of antiaircraft anti aircraft artillery 4 7 A ve V X r MINI PA ma ga 7 Y Z photograph shows one of the new streamlined sound detectors the army tested during the air corps and aircraft defense maneuvers in north carolina the listening horns are made of balsa wood with rounded edges and a cellulose acetate covering they have no greater hearing power than the old style but are more eff effective active in shutting out all but plane noises thus searchlights and guns of the antiaircraft anti aircraft bit batteries teries can be trained more efficiently on attacking planes |