Imagine three people huddled in a circle so when one speaks, only one other hears. Scientists have created a device that works like that, ensuring sound waves ripple in one direction only.
The device, developed by scientists at ETH Zurich and the Swiss Federal Institute of Technology Lausanne, is made up of a disk-shaped cavity with three equally-spaced ports that can each send or receive sound.
In an inactive state, sound transmitted from port 1 is audible to ports 2 and 3 at equal volumes. Sound waves bounce back to port 1 as an echo as well.
When the system is running, however, only port 2 hears port 1’s sounds.
The trick is to blow swirling air into the cavity at a specific speed and intensity, which allows the sound waves to synchronize in a repeating pattern. That not only guides the [sound waves](https://www.sciencealert.com/sound-really-can-travel-in-a-vacuum-and-we-can-finally-explain-how) in a single direction, but gives more energy to those oscillations so they don’t dissipate. It’s kind of like a roundabout for sound.
The scientists say their technique may inform the design of future communications technologies. New metamaterials could be made to manipulate not just sound waves but potentially electromagnetic waves too.
Could this be used to direct train horn energy with high directionality down the track? Would be nice not to disturb the entirety of so many towns multiple times per day when only the crossings need to hear it.
noother10 on
Could this be a real cone of silence?
m15otw on
There have been speakers that do this for ages, right? That’s what they use at festivals to project sound all the way to the back of the crowd without deadening those at the front?
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Summary of the article in ScienceAlert:
Imagine three people huddled in a circle so when one speaks, only one other hears. Scientists have created a device that works like that, ensuring sound waves ripple in one direction only.
The device, developed by scientists at ETH Zurich and the Swiss Federal Institute of Technology Lausanne, is made up of a disk-shaped cavity with three equally-spaced ports that can each send or receive sound.
In an inactive state, sound transmitted from port 1 is audible to ports 2 and 3 at equal volumes. Sound waves bounce back to port 1 as an echo as well.
When the system is running, however, only port 2 hears port 1’s sounds.
The trick is to blow swirling air into the cavity at a specific speed and intensity, which allows the sound waves to synchronize in a repeating pattern. That not only guides the [sound waves](https://www.sciencealert.com/sound-really-can-travel-in-a-vacuum-and-we-can-finally-explain-how) in a single direction, but gives more energy to those oscillations so they don’t dissipate. It’s kind of like a roundabout for sound.
The scientists say their technique may inform the design of future communications technologies. New metamaterials could be made to manipulate not just sound waves but potentially electromagnetic waves too.
Read the full paper here: [https://www.nature.com/articles/s41467-024-51373-y](https://www.nature.com/articles/s41467-024-51373-y)
Could this be used to direct train horn energy with high directionality down the track? Would be nice not to disturb the entirety of so many towns multiple times per day when only the crossings need to hear it.
Could this be a real cone of silence?
There have been speakers that do this for ages, right? That’s what they use at festivals to project sound all the way to the back of the crowd without deadening those at the front?