Sound transmission through finite lightweight multilayered structures with thin air layers

Abstract

The sound transmission loss (STL) of finite lightweight multilayered structures with thin air layers is studied in this paper. Two types of models are used to describe the vibro-acoustic behavior of these structures. Standard transfer matrix method assumes infinite layers and represents the plane wave propagation in the layers. A wave based model describes the direct sound transmission through a rectangular structure placed between two reverberant rooms. Full vibro-acoustic coupling between rooms, plates, and air cavities is taken into account. Comparison with double glazing measurements shows that this effect of vibro-acoustic coupling is important in lightweight double walls. For infinite structures, structural damping has no significant influence on STL below the coincidence frequency. In this frequency region, the non-resonant transmission or so-called mass-law behavior dominates sound transmission. Modal simulations suggest a large influence of structural damping on STL. This is confirmed by experiments with double fiberboard partitions and sandwich structures. The results show that for thin air layers, the damping induced by friction and viscous effects at the air gap surfaces can largely influence and improve the sound transmission characteristics.

Numerical Investigation of the Repeatability and Reproducibility of Laboratory Sound Insulation Measurements

“…Especially above the mass-spring-mass resonance frequency, the sound reduction index is more sensitive to the parameters investigated. Because the sound transmission through double glazing is strongly dependent on the angle of incidence in this frequency range, the influence of the source room dimensions, the aperture position and the aperture dimensions -which determine the directional distribution of incident energy -is more pronounced [27,28].…”

“…Previously, a wave based model has been developed to describe the direct sound transmission through multilayered walls between two reverberant rooms [27,28]. With this model, the sound insulation of rectangular single and double walls placed between two rectangular rooms can be investigated.…”

Finite element reduced order model for noise and vibration reduction of double sandwich panels using shunted piezoelectric patches

“…For a finite size flat panels, a theoretical study, based on Fourier series expansions, is presented in [4] concerning the vibroacoustic performance of a rectangular double-panel mounted in an infinite acoustic rigid baffle. Experimental evaluation of sound transmission through single, double and triple glazing can be found in [5][6][7][8]. Regarding the numerical prediction approaches, several methods are available in the literature, such as the Finite Element Method (FEM), the Boundary Element Method (BEM) and the Statistical Energy Analysis (SEA).…”

Modal-based prediction of sound transmission through slits and openings between rooms

“…In [5] finite elements are used in order to make a more accurate description of the partition and consider a double wall. Layered partitions are also considered in [6] by means of wave-based and transfer matrix-based models that take into account modal coupling between the problem subsystems as well as corrections due to the finite dimensions of the problem.…”