Omnidirectional acoustic absorber with a porous core and a metamaterial matching
layer

Elliott, A S; Venegas Castillo, RG; Groby, JP; Umnova, O

Abstract

An omnidirectional sound absorber based on the acoustic analogy of the electromagnetic metamaterial
“black hole” has been developed and tested. The resulting structure is composed of a hollow
cylindrical porous absorbing core and a graded index matching layer which employs multiple rods of
varying size and spacing to gradually adjust the impedance of the air to that of the porous absorbing
core. A semi-analytical model is developed, and the practical challenges and their implications with
respect to performance are considered. A full size device is built and tested in an anechoic chamber
and the semi-analytical model used in the design process is validated. Finally, the theory is extended
to allow for losses in the metamaterial matching layer, and it is shown that improved performance may
be achieved with a dual purpose layer which acts as an absorber whilst also providing the required
impedance matching condition.

Citation

layer. Journal of Applied Physics, 115(20), 204902. https://doi.org/10.1063/1.4876119

• Journal Article Type: Article
• Acceptance Date: Apr 30, 2014
• Publication Date: May 22, 2014
• Deposit Date: May 29, 2015
• Publicly Available Date: Apr 5, 2016
• Journal: Journal of Applied Physics
• Print ISSN: 0021-8979
• Electronic ISSN: 1089-7550
• Publisher: AIP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 115
• Issue: 20
• Pages: 204902
• DOI: https://doi.org/10.1063/1.4876119
• Publisher URL: http://dx.doi.org/10.1063/1.4876119
• Related Public URLs: http://scitation.aip.org/content/aip/journal/jap