Ultra-thin metamaterial for perfect and quasi-omnidirectional sound absorption

Abstract

Using the concepts of slow sound and critical coupling, an ultra-thin acoustic metamaterial panel for perfect and quasi-omnidirectional absorption is theoretically and experimentally conceived in this work. The system is made of a rigid panel with a periodic distribution of thin closed slits, the upper wall of which is loaded by Helmholtz Resonators (HRs). The presence of resonators produces a slow sound propagation shifting the resonance frequency of the slit to the deep sub-wavelength regime (lambda/88). By controlling the geometry of the slit and the HRs, the intrinsic visco-thermal losses can be tuned in order to exactly compensate the energy leakage of the system and fulfill the critical coupling condition to create the perfect absorption of sound in a large range of incidence angles due to the deep subwavelength behavior.

@article{jimenez2016ultra,
 author = {Noé Jiménez and Weichun Huang and Vicent Romero-García and Vincent Pagneux and Jean-Philippe Groby},
 doi = {http://dx.doi.org/10.1063/1.4962328},
 issn = {0003-6951},
 journal = {Applied Physics Letters},
 month = {9},
 number = {12},
 pages = {121902},
 publisher = {AIP Publishing},
 title = {Ultra-thin metamaterial for perfect and quasi-omnidirectional sound absorption},
 url = {http://scitation.aip.org/content/aip/journal/apl/109/12/10.1063/1.4962328},
 volume = {109},
 year = {2016}
}