Destructive interferences in resonators created using additive manufacturing

Abstract

The broad absorption of low-frequency noise typically requires the utilization of large thicknesses of sound absorbing materials. As this creates space issues, there is a demand for thin broad low-frequency absorbers. This research aims to develop an acoustic transparent panel for low-frequency broad sound absorption. Destructive sound resonance tubes were created for this scope using modern tools for generating complex geometries in systems of a few centimeters of thickness. The capability of digital fabrication to enable design freedom and to support the production of complex geometries is explored in this paper. Destructive interference means that two interfering sound waves that are in counter-phase, cancel each other. Digital fabrication is shown to play an important role in developing customized sound absorbing components to absorber below 500 Hz, and especially well below 200 Hz. A parametric script using Grasshopper through Rhinoceros to generate automatically the geometric parameters of the 3d resonators is described. Different materials for 3d printing the resonators are compared. Finally, the challenges of additive manufacturing techniques are finally reported.