them's some big horns
The sound goes the OTHER WAY.
These are listening devices from before RADAR was invented.
Pairs of these horns come together at a pivot point which is at the top of the center mast, and this DUDE sits up there, listening for the noise of approaching aircraft engines in the sky. Other guys swing this whole thing around, or up and down until he says the left/right sound is equal. Then you can point ground based guns in the same direction as the horns, cross your fingers, and see if you knock any of 'em down...
