The AUDIO invisibility cloak: One-way sound device could let spies listen in on people without being heard

The AUDIO invisibility cloak: One-way sound device could let spies listen in on people without being heard The one-way sound machine is called an acoustic circulator Waves traditionally travel forward before reversing and bouncing back With sound, this lets you speak, hear yourself speak, and hear responses The circulator chambers move waves through its three-port formation Fans change the flow of air and stop the sounds from bouncing back Scientists in Texas claim it works in a similar way to one-way glass 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. Called an acoustic circulator, the first-of-its-kind system uses fans to change the flow of air as the sound waves travel through it, and this prevents the waves from bouncing back. When the fans were turned off, the sound signal from Port 1 split in half and travelled through the two other ports, Port 2 and Port 3, as expected - known as ‘transmission symmetry’. 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.