2024-11-24T02:13:13-05:00 https://archinect.com/news/article/150125927/this-new-acoustic-metamaterial-can-cancel-the-sounds-of-anything-without-blocking-airflow Alexander Walter 2019-03-11T14:16:00-04:00 >2019-03-11T14:17:45-04:00 <img src="https://archinect.gumlet.io/uploads/80/808404488f84300508e66d4d730bb0d7.jpg?fit=crop&auto=compress%2Cformat&enlarge=true&w=1200" border="0" /><em><p>A team of Boston University researchers recently stuck a loudspeaker into one end of a PVC pipe. They cranked it up loud. What did they hear? Nothing. How was this possible? Did they block the other end of the pipe with noise canceling foams or a chunk of concrete? No, nothing of the sort. The pipe was actually left open save for a small, 3D-printed ring placed around the rim. That ring cut 94% of the sound blasting from the speaker, enough to make it inaudible to the human ear.</p></em><br /><br /><p>"The mathematically designed, 3D-printed acoustic metamaterial is shaped in such a way that it sends incoming sounds back to where they came from," <a href="https://www.eurekalert.org/pub_releases/2019-03/bu-brd030619.php" rel="nofollow" target="_blank">explain</a> the Boston University researchers behind the discovery: Xin Zhang, a professor at the College of Engineering, and Reza Ghaffarivardavagh, a Ph.D. student in the Department of Mechanical Engineering. "Inside the outer ring, a helical pattern interferes with sounds, blocking them from transmitting through the open center while preserving air's ability to flow through."</p> <p>Precisely this capacity of maintaining airflow and enabling light to shine through while muting nearly all of the noise opens up a vast field of practical applications, including architectural.</p>