Phys.org December 7, 2021 According to the researchers in Hong Kong the absence of shear force in the air, or fluids, makes sound waves longitudinal. Synthetic shear force may arise if the air is discretized into “meta-atoms,” whose collective motion can give rise to a transverse sound on the macroscopic scale. To implement this idea they designed micropolar metamaterial like a complex network of resonators. Air was confined inside the mutually connected resonators, forming the meta-atoms. Through theoretical calculations they showed that the collective motion of meta-atoms produces the shear force, which gives rise to the transverse sound with spin-orbit […]
Category Archives: Acoustics
Breaking the symmetry of sound waves allows the sound to be directed to a certain place
Phys.org November 29, 2021 An international team of researchers (China, Spain) constructed a topological gallery insulator using sonic crystals made of thermoplastic rods that are decorated with carbon nanotube films, which act as a sonic gain medium by virtue of electro-thermoacoustic coupling. By engineering specific non-Hermiticity textures to the activated rods, they were able to break the chiral symmetry of the whispering-gallery modes, which enables the out-coupling of topological ‘audio lasing’ modes with the desired handedness. Adding gain makes it possible to amplify to break the chiral symmetry. The laboratory tests have demonstrated that when these elements are applied, the […]