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International audienceThis study examines the acoustic properties of materials with complex micro-geometry containing partially open or dead-end porosity. One of these kinds of materials can be obtained from dissolving salt grains embedded in a solid metal matrix with the help of water. The solid matrix is obtained after the metal in liquid form has invaded the granular material formed by the salt particles at negative pressure and high temperature, and after cooling and solidification of the metal. Comparisons between theoretical and experimental results show that the classical Johnson-Champoux-Allard model does not quite accurately predict the acoustic behavior. These results suggest that the assumptions of the Biot theory may not be all fulfilled and that Helmholtz-type resonators and dead ends can be present in the material. The first part of the study proposes a simple model to account for this geometry. Based on this model, two acoustic transfer matrices are developed: one for non symmetric and one for symmetric dead-end porous elements. This model can be used to study the acoustic absorption and sound transmission properties of the type of material described above. In the second part, a series of simplified samples are proposed and tested with a three-microphone impedance tube to validate the exposed model. Finally, the third part compares predictions of the exposed model to impedance tube results on a real aluminum foam sample containing dead-end pores

Acoustic properties of air-saturated porous materials containing dead-end porosity