Newly developed cloak hides underwater objects from sonar

Newly developed cloak hides underwater objects from sonar: "ScienceDaily (Jan. 6, 2011) — In one University of Illinois lab, invisibility is a matter of now you hear it, now you don't. Led by mechanical science and engineering professor Nicholas Fang, Illinois researchers have demonstrated an acoustic cloak, a technology that renders underwater objects invisible to sonar and other ultrasound waves."