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http://weblogs.baltimoresun.com/.../blog/engineering/

Harry Potter's invisibility cloak it ain't. But Duke University researchers, who in 2006 developed the first proof-of-concept device capable of hiding an object from electromagnetic radiation (meaning light), now say a similar device could shield objects from sound waves.

The team, led by Steven Cummer, an engineering professor at Duke's Pratt School of Engineering, developed a mathematical proof that suggests the same cloaking shell that was developed in 2006 could be modified so that it wouldn't reflect sound waves.

Acoustic waves would instead pass undisturbed around objects placed inside. The concept had previously been proven in two dimensions, but Cummer says his group has shown its possible in 3D.

Sound cloaks might one-day hide submarines from sonar detection or improve the acoustics of a theater by bending sounds around beams and obstructions.

A paper explaining the theory will appear in the Jan. 13 edition of the journal Physical Review Letters and an announcement of the finding is posted on the Duke Web site.