One-way sound device lets you spy on someone without being heard

Stealth isn’t just something you learn in video games like Thief and Assassins Creed. In real-world applications, stealth is key for things like spying and military maneuvers. It’s no wonder then that technology is evolving to create situations where stealth is easier for those involved.

We’re already working on invisibility cloaks, but those are useless if you’re sneaking around and trip on something, falling down and making noise. But what if you had a device that kept you from being heard, but allowed you to still hear everything going on around you? That’s exactly what researchers at the University of Texas at Austin have developed: an acoustic isolator device that lets you hear others, but keeps them from hearing you.

What’s most remarkable about this device, called a one-way acoustic circulator, is that its concept is relatively simple, even though it breaks a basic law of physics that states if sound waves travel in one direction, they must travel in the opposite direction. However, think about what happens when you’re standing in a heavy wind and trying to shout: your voice is barely heard if the wind is strong enough. Well, the acoustic circulator sort of works on that same idea.

The device, shaped like a hexagon, contains three fans, just like those found in your computer. On each end of the device are ports containing microphones. Those three ports act as “acoustic waveguides,” and transmit sound from one port to another. When the fans are off, sound travels normally, through all three ports. Switch the fans on, though, and direct their airflow, and sound only travels in the direction the fans are turned away from.

So imagine you’re James Bond and hiding under your invisibility cloak. You’ve got your acoustic isolator with you. You hear everything the enemy is saying, but the enemy doesn’t hear you. You communicate via your high-tech earpiece to headquarters without being heard, all the while getting the information you need for your mission. But, obviously, that’s not all this technology can do. It could also prevent noise pollution (perhaps blocking out sound in a house that’s near a busy highway or airport) and used for stealth vehicles for the military. The UT Austin researchers are working on a smaller device and it’s a sure bet that it will find itself put to good use soon, at least by guys like James Bond.

Via ExtremeTech

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