CD 1963038 E&MP 21.026
June 9, 1949
A new "silent" engine-generator set, scheduled for service tests in the near future, is shown here in its sound-muffling box.
The glass-wool lining and labyrinthed air ducts reduce the noise of the set in operation by 25 decibels.
Virtually inaudible at a range of 200-325 feet under quiet atmospheric conditions, the machine was developed by the Corps of Engineers Research and Development Laboratories, Fort Belvoir, Virginia.
Original Caption by Science Service
©United States Army