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These Bricks Can Absorb Traffic Noise - Thesis Presentation on Helmholtz Resonators
(www.youtube.com)
Technology for a Solar-Punk future.
Airships and hydroponic farms...
In that case, someone should work on my idea instead: drones that use an array of microphones to pinpoint where a car horn comes from, and launches rotten eggs at it.
There's a good reference prototype you can check, it's from the early 2000's featuring its debut in Malcolm in the Middle!