Experimental Analysis of Acoustics Characteristics of Honeycomb-Backed MPP Panel with Different Material Elasticities

This paper discusses the experimental analysis of the sound absorption coefficient and transmission loss of hybrid panels made of a multi-perforated panel (MPP) backed by a honeycomb structure with different material elasticities. The panels are created using 3D printing and made of thermoplastic polyurethane (TPU) filament, which is more flexible than the second material, polylactic acid (PLA) filament. This study aims to compare the effect of material flexibility on the panel’s acoustic properties. The acoustics are measured using a four-channel impedance tube following ASTM E2611-19. The panels have various panel thicknesses, honeycomb wall and MPP thicknesses, and MPP hole densities. The study indicates that as panel thickness increases, the peak of the sound absorption coefficient is shifted to a lower frequency, resulting in enhanced sound insulation. When MPP hole density decreases, the number of MPP holes decreases, and the absorption coefficient and sound insulation increase. Furthermore, TPU panels have a lower sound absorption frequency than PLA and slightly higher insulation than PLA. As a result, material flexibility does not significantly affect the maximum sound absorption coefficient and sound transmission loss; more flexible panel material shifts the sound absorption coefficient peak to a lower frequency.