Ultra-thin metamaterial for perfect and omnidirectional sound absorption

By N. Jim'enez, Weichun Huang, V. Romero-García, Vincent Pagneux, J. Groby. 2016

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Using the concepts of slow sound and of critical coupling, an ultra-thin acoustic metamaterial panel for perfect and 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.

Subfields: Biomedical Engineering, Electronic, Optical and Magnetic Materials, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/8607561bdee3c411a8324324027201d278a6d642