SOUND MIRROR (200 FEET)

SN A concrete, concave wall 200 feet in length used as an acoustic listening device to detect approaching enemy aircraft.
CL MILITARY DEFENCE AND FORTIFICATION
BT SOUND MIRROR

 
 

SOUND MIRROR (200 FEET)

SN A concrete, concave wall 200 feet in length used as an acoustic listening device to detect approaching enemy aircraft.
CL MILITARY DEFENCE AND FORTIFICATION
BT SOUND MIRROR