"SENSORS:Researchers claim cloak can render subs invisible to sonar"

Duke University engineers will reveal Friday (Jan. 11) details of an acoustic cloak fabricated from metamaterials that they claim can render objects invisible to sonar. Although the acoustic cloak has only been mathematically simulated, the engineers claim that devices based on their blueprint can make submarines invisible to sonar. They work by redirecting sound waves around the hull so that they emerge on the other side without distortion.