An efficient hybrid transfer matrix-statistical energy analysis approach for predicting the sound transmission through thick and layered walls
In this work, an efficient method is developed for computing the diffuse sound transmission of walls and floors that consist of layers of solid, fluid and/or poroelastic material. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes, which obviates the need for numerically integrating the plane wave transmission coefficient for all possible angles of incidence. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. The method is applied for predicting the airborne sound insulation of a thin plate, a thick wall and a sandwich panel. The predictions are compared with alternative predictions and with measured values. A good overall agreement is observed.
Acoustic and vibration response of a structure with added noise control treatment under various excitations.
The evaluation of the acoustic performance of noise control treatments is of great importance in many engineering applications, e.g., aircraft, automotive, and building acoustics applications. Numerical methods such as finite- and boundary elements allow for the study of complex structures with added noise control treatment. However, these methods are computationally expensive when used for complex structures. At an early stage of the acoustic trim design process, many industries look for simple and easy to use tools that provide sufficient physical insight that can help to formulate design criteria. The paper presents a simple and tractable approach for the acoustic design of noise control treatments. It presents and compares two transfer matrix-based methods to investigate the vibroacoustic behavior of noise control treatments. The first is based on a modal approach, while the second is based on wave-number space decomposition. In addition to the classical rain-on-the-roof and diffuse acoustic field excitations, the paper also addresses turbulent boundary layer and point source (monopole) excitations. Various examples are presented and compared to a finite element calculation to validate the methodology and to confirm its relevance along with its limitations.
A simple method to account for size effects in the transfer matrix method.
The transfer matrix method based is extensively used and well-validated for predicting the transmission loss of multilayer structures. However, this method leads to poor results at low frequencies due to the infinite extent assumption it is based on. This paper presents an efficient implementation of a Rayleigh-integral based method to account for the finite size effects. The accuracy of the method is illustrated by various examples.