E-Mail EUGENE, Ore. -- April 16, 2021 -- University of Oregon physicists have developed a new method to manipulate sound -- stop it, reverse it, store it and even use it later -- in synthetic composite structures known as metamaterials. The discovery was made using theoretical and computational analysis of the mechanical vibrations of thin elastic plates, which serve as the building blocks for the proposed design. The physicists, Pragalv Karki and Jayson Paulose, also developed a simpler minimal model consisting of springs and masses demonstrating the same signal manipulation ability. "There have been a lot of mechanisms that can guide or block the transmission of sound waves through a metamaterial, but our design is the first to dynamically stop and reverse a sound pulse," said Karki, a postdoctoral researcher in the UO's Department of Physics and Institute for Fundamental Science.