Impedance tube measurements of 3D printed porous materials

Abstract

The acoustics of porous media affects what materials are good for sound control in enclosed environments. The theories used in this area model porous materials as having continuous unconnected pores. The important physical factors in these theories are the porosity (ratio of pore volume to sample volume), tortuosity (ratio of pore length to sample depth), and flow resistivity (resistance to air flow through the sample). The models allow for calculation of acoustic properties but are not truly representative of most porous media. With the advent of 3D printing, it is possible to design and print 3D media with specific porosity and tortuosity characteristics. These materials can be used in an impedance tube to test the validity of the models being used. Porous plugs will be designed and 3D printed using stereolithography. The plugs’ acoustic properties will be measured in an impedance tube. The results of this project will provide data that can be used to refine the acoustic models of porous media.