[link|http://www.nytimes.com/2005/05/30/technology/30hillis.html?ex=1275105600&en=4a1c68b85a47519f&ei=5090&partner=rssuserland&emc=rss|http://www.nytimes.c...suserland&emc=rss]
The cone of silence, called Babble, is actually a device composed of a sound processor and several speakers that multiply and scramble voices that come within its range. About the size of a clock radio, the first model is designed for a person using a phone, but other models will work in open office space.
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I wonder whether the NSA will insist on disclosure of the algorithm to allow government surveillance.