The centre of the acoustic circulator, pictured, is fitted with three specially positioned fans that change the flow of air through the separate chambers
Spies around the world could soon be able to listen in on secret conversations without any fear of being found out thanks to the first ever one-way sound machine.
Sound waves traditionally travel forward before bouncing back, and with sound this means you can speak, hear yourself speak, and hear any responses.
An 'acoustic circulator' which is the first of its kind, uses fans to change the flow of air as sound waves travel through it and this prevents the waves from bouncing back.
The circulator was created by a team of researchers in the Department of Electrical and Computer Engineering at The University of Texas at Austin led by Professor Andrea Alu.
Professor Alu said his experiments successfully prove that the 'fundamental symmetry with which acoustic waves travel through air between two points in space - for example, if you can hear, you can also be heard - can be broken by a compact and simple device'.
The inspiration for the device came from current three-port electronic circulators that are typically used in communication devices and radars.
For example, Microwaves and radio signals are able to move from one port to the next in sequence, meaning they're never sent back to the recipient.
In these electronic circulators, when one of the ports isn’t being used, the system acts as an isolator, letting signals to flow from one port to the other, but not back.
The UT Austin team realised the same principles could apply from sound waves traveling in air, which led to the team's building of a first-of-its-kind three-port acoustic circulator.
'Using the proposed concept, we were able to create one-way communication for sound traveling through air,' Professor Alu said.
