MUSEUM "WAALSDORP"

Listening cage

	After elimination of all interfering noises of mechanical origin at adjusting the listening equipment only one single source remained. The nearly always present wind caused noise due to turbulence around parts of the listening equipment. This noise was decreased by use of a listening cabin. The cabin was built up around the listening equipment by a reinforcement steel frame covered with a thin more or less transparent jute cover. Without this cage the equipment was inoperable with a wind speed of 4 m/sec. Using the cage however listening was still possible with 6 m/sec. A second advantage was that the listener was not disturbed by movements in his field of view. To the disappointment of the Measurements Building, the military authorities did not support the further development, apparently in the belief that the cage was too impractical.		Reinforcement steel frame of the listening equipment (full size 147 KB) Listening equipment covered with jute sheet (full size 119 KB)