Zhuang Mo, Guochenhao Song, Tongyang Shi and J. Stuart Bolton, “Acoustic Modeling of Granular Material and its Combination with a Flexible Perforated Membrane,” paper presented at the Symposium on the Acoustics of Poro-Elastic Materials, SAPEM ’23, Sorrento, Italy, and Changshu, China, 7-10 November, 2023.


Porous granular materials such as activated carbon have been found helpful in sound absorption at low frequencies, and enlarging the apparent volume of loudspeaker cabinet. Such findings have encouraged studies of modeling technique to predict their response to an acoustic input. When tested in an impedance tube, the finite space of the sample holder and the elasticity of the granule stack can lead to features that are not predicted by rigid acoustic models, like sound absorption peaks caused by radial modes, for example. In the presented work, a finite difference (FD) scheme is built based on Biot theory to account for both the coupling between the solid and fluid phases of the granule stack, and the cylindrical shape of impedance tube sample holder. Further, the performance of sound absorbers consisting of a membrane and granules that partially fills the backing cavity is simulated following this numerical approach.


Granular materials, Activated carbon, Perforated membrane, Sound absorption, Finite difference model


Acoustics and Noise Control

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