UC Berkeley physicists have created ultrasonic, lightweight loudspeakers and microphones that will enable people to echolocate like bats and dolphins.
The wireless ultrasound devices complement standard radio transmission using electromagnetic waves in areas where radio is not practical, such as underwater, but with far greater fidelity than current ultrasound or sonar devices.
They can also be used to communicate through objects, such as steel, that electromagnetic waves cannot penetrate.
The device is made with graphene that consists of carbon atoms laid out in a hexagonal, chicken-wire arrangement, which creates a tough, lightweight sheet with unique electronic properties.
Source & further reading:http://news.berkeley.edu/2015/07/06/bats-do-it-dolphins-do-it-now-humans-can-do-it-too/