Scientists from the University of Illinois, US, have developed and successfully demonstrated an acoustic metamaterial cloak that could make submarines completely invisible to sonar and other ultrasound waves.
Mechanical science and engineering professor Nicholas Fang and his team have tried testing the technology on objects with different materials and densities and proved that the cloak could make objects invisible to a broad range of sound waves.
"We are not talking about science fiction. We are talking about controlling sound waves by bending and twisting them in a designer space," he said.
The metamaterial cloak consists of 16 concentric rings of acoustic circuits that bend the sound waves to wrap them around the outer layers of the cloak making it appear invisible.
According to an Australian Government report, military sonar systems generally operate from 1,000Hz to 500kHz and the cloak is capable of covering sound wavelengths, from 40kHz to 80kHz.
The technology could also be used by other areas of submarine stealth including cavitation, through which small bubbles form and burst around fast moving objects such as propeller blades.