Effects of mounting positions and boundary conditions on the sound transmission loss of panels in a niche

Abstract

The sound insulation performance of railway car body structures is critical for the control of rail vehicle interior noise. In sound transmission loss (STL) measurements, a niche with a large depth is necessary to allow for mounting the wide range of thicknesses of railway car body panels and for the mechanical isolation of the two rooms. In this study, two typical interior floor panels are tested in a series of mounting conditions and mechanical boundary conditions. The change of STL results during measurement is also predicted by an STL prediction model based on the finite element method. At lower frequencies, the STL results are influenced by both the mounting positions and the mechanical boundary conditions. At higher frequencies, the STL results are mainly influenced by the mechanical boundary conditions. Differences between the panel in the infinite baffle and niches at the resonance and off-resonance frequencies are different. Considering both the effects of mounting positions and mechanical boundary conditions, the existence of the cavity amplifies the STL difference caused by the mechanical boundary conditions.