Science Technology A New 'Mathematically Perfect' Material Could Completely Swallow Sound By Christian Cotroneo Social Media Editor Brock University Carleton University Christian Cotroneo is the social media editor at Treehugger. He is a founding editor at HuffPost Canada, and former writer at The Dodo and Toronto Star. our editorial process Christian Cotroneo Updated March 09, 2019 Deceptively simple, the 3D-printed material is a mathematical marvel. Cydney Scott, Boston University Share Twitter Pinterest Email Science Space Natural Science Technology Agriculture Energy These days, silence isn't just golden. It's far much more precious and rare than that. Think diamond. Or plutonium, which reportedly goes for around $4,000 a gram. In fact, the way we're going — with humans and their bustling cars and trains and infernal Bluetooth speakers — silence may soon be the most precious thing on Earth. The trouble is our means of acquiring silence hasn't kept up with the times. We're still stuffing our ears with foam when the guy in the unit upstairs rocks out. Or hoping against hope that the walls separating us from the countless neighbors above and below can save us. "Today's sound barriers are literally thick heavy walls," notes mathematician Reza Ghaffarivardavagh in a recent press release. But Ghaffarivardavagh, along with colleagues at Boston University, may have finally come up with the most sanity-inducing invention of the 21st century: a material capable of swallowing sound. Dubbing it an "acoustic metamaterial," the researchers shared their work this month in a paper published in Physical Review B. Essentially, they treated noise like a mathematical problem, and used a mathematical construct to nullify it. Behold, the cone of silence — a ring-like structure designed to remove sound, while allowing air to flow through it. Sure, that looks a little bit larger than the set of earplugs beside your bed. Not the kind of thing you can probably squeeze comfortably in your ears. But keep in mind, that's just the prototype for research purposes — basically a long PVC tube lined with what researchers call an "acoustic metamaterial." That's the real wonder here: a mathematically perfect material that's 3D-printed that could be inserted anywhere and could be custom designed for a specific sound. For their experiment, the Boston University researchers printed material specifically designed to silence the thunder from a loudspeaker. Their calculations resulted in a plastic tube that swallowed the sound from a loudspeaker on one end and offered nothing but clean quiet air on the other end. The metamaterial, made from paper and aluminum, completely silenced the boom of the loudspeaker. When a researcher removed that material from the end of the tube, the experiment took a thunderous turn. "The moment we first placed and removed the silencer ... was literally night and day," co-author Jacob Nikolajczyk noted in the release. "We had been seeing these sorts of results in our computer modeling for months — but it is one thing to see modeled sound pressure levels on a computer, and another to hear its impact yourself." Think of this giant tube as the anti-telephone game. Someone speaks in one end of the tube — and you just feel the gust of their breath. Now, think of the future as we finally find peace in an increasingly unpeaceful world. Researchers are already rhyming off a litany of real-world uses. Like, for instance, when Amazon inevitably starts filling the air with door-to-door delivery drones. Outfitted with acoustic metamaterial, these drones could be completely muted. Then there's the bane of anyone who has ever lived below a chronic cleaner: the vacuum cleaner. "Our structure is super lightweight, open, and beautiful," researcher added in the release. "Each piece could be used as a tile or brick to scale up and build a sound-canceling, permeable wall." And with each piece added to our thin apartment walls, a little more of that precious peace we all need. But the best part? The material not only strips the sound of the air, it sends it back where it came from. So take that, guitar-hero-who-lives-upstairs.