Efficient and robust coupling of finite element and diffuse field models for sound transmission prediction

Invited paper

Edwin Reynders

KU Leuven Dept. of Civil Engineering

Wednesday 3 june, 2015, 14:40 - 15:00

Auditorium 2 (592)

Predicting the airborne or structure-borne sound transmission through a real-life building element generally requires a detailed model of that element. Simplified analytical structural models based on infinite thin plate theory are very important for gaining insight into the physical principles of the sound transmission process, but they are inaccurate when the modal behavior of the building element is important or when the geometry of the wall is complex. A commonly adopted strategy therefore consists of constructing a detailed finite element model and computing the expected value of the sound reduction index by numerically integrating the plane-wave transmission over all angles of incidence. This is not only computationally costly, but all information on the uncertainty of the predicted values due to the statistical nature of the diffuse acoustic field model is also lost. An alternative, more efficient method for coupling a finite element model of a building element to diffuse field models of the rooms has been recently presented. It is based on two recent developments in diffuse field theory: a direct field - diffuse field reciprocity relationship and the the Gaussian Orthogonal Ensemble model for the natural frequencies and mode shapes of a diffuse component. Both the mean and variance of the sound reduction index can be computed, so that the uncertainty of the predicted values due to the diffuse acoustic field assumption can be assessed. In this work, the method is employed for predicting the sound transmission through building elements of increasing complexity. The predictions are validated against available measurement data, and it is found that the proposed approach can capture both the complex dynamics of the walls and the uncertainty of the generalized diffuse field assumption of the acoustic fields.

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