I was browsing through the US Air Force's official Flickr photostream today when I came across this picture of a CV-22 Osprey aircraft, its rotors folded, hanging in the anechoic chamber of the 'Joint Preflight Integration of Munitions and Electronic Systems (J-PRIMES)' hangar at Eglin Air Force Base in Florida.
The entry notes that J-PRIMES "is a room designed to stop internal reflections of electromagnetic waves as well as insulate from exterior sources of electromagnetic noise. J-PRIMES provides this environment to facilitate testing air-to-air and air-to-surface munitions and electronics systems on full-scale aircraft and land vehicles prior to open-air testing."
I looked for more information, and found a useful article on Wikipedia about such chambers. Apparently they're built in two different versions. One provides insulation from external sound - the ultimate in 'soundproof rooms', if you will. (Gizmodo refers to Microsoft's anechoic sound chamber as being 'The Place Where Sound Goes To Die', and describes it as 'freaky'.) The other type (like that pictured above) insulates from electromagnetic waves, so that electronic systems can be tested inside it, free from external interference. They're said to be so effective that being inside one while it's in use may be hazardous to your health.
Anyway, the picture intrigued me; so I thought you might find it interesting too. The aircraft alone cost about $70 million at FY2012 prices, and the anechoic chamber doesn't look like it cost chump change either. Our tax dollars at work!