Implementation of diffraction in a ray-tracing model for the prediction of noise in open-plan offices

Abstract

Sound prediction in open-plan offices is a real challenge because of the complexity of the layout of such offices, and therefore because of the multitude of acoustic phenomena involved. One such phenomenon, of primary importance, and not the least challenging of them, is the diffraction by screens and low dividers that usually partition the workspace. This paper describes implementing the equations of the Uniform Theory of Diffraction [McNamara et al. (1990). Introduction to the Uniform Theory of Diffraction (Artech House, Boston)] in an existing ray-tracing model initially dedicated to sound prediction in industrial premises. For the purposes of validation, a series of measurements was conducted in a semi-anechoic chamber in the same manner as Wang and Bradley [(2002). Appl. Acoust. 63, 849-866] but including real desktops instead of single screens. A first phase was dedicated to controlling the quality of the installation by making comparisons with McNamara's solution for a single screen on a rigid floor. Then, the validation itself was conducted with measurements on real desktops, first without a ceiling, and then with a rigid ceiling suspended above the double desk. The results of the comparisons between calculations and measurements in this configuration have demonstrated that the model is an effective tool for predicting sound levels in an open-plan office.

Recent advances in building acoustics: An overview of prediction methods and their applications

“…Many recent studies in the geometrical acoustics method are about wave-based phenomena such as diffraction [15][16][17][18][19]. Allen and Berkley were the first to show that for the special case of a rigid rectangular room the mirror source method yields an equivalent result to the solution of the Helmholtz equation [20].…”

“…Some recent works in ray tracing focused on developing fast sound propagation algorithms for interactive scenes [27][28][29]. Chevret and Chatillon [16] applied diffraction theory and the ray tracing model to the prediction of noise in open-plan offices. For traffic noise break-in, Chen et al [30] recently incorporated a space partitioning method into the 3-D ray tracing method.…”

“…A C C E P T E D ACCEPTED MANUSCRIPT 16 Del Rey et al [81] investigated an empirical model for predicting sound absorption performance of recycled foam materials by following the Dunn and Davern and the Voronina models. Liu et al [82] investigated the use of a regression neural network to derive a method to predict sound absorption coefficients of sandwich structure nonwoven absorbers based on the results of a series of measurements of thickness, area density, porosity, and the pore size of each layer.…”

Effects of the Top Edge Impedance on Sound Barrier Diffraction

“…However, these conventional analytical methods are no longer capable of dealing with the barriers with complex profiles and complex impedances, where the BEM becomes a good option [26,27]. The basic formulation and implementation of a collocation BEM are well established, but they generally consume large amounts of computing resources and errors may arise when performing discretization and solving integrations [28,29].…”

A preliminary study on the performance of indoor active noise barriers based on 2D simulations

“…Chevret and Chatillon described a model for predicting diffraction in complex spaces by using the ray-tracing method in 2012, which belongs to the family of incoherent methods. A phaseincluded expression of the existing model was developed recently in 2014, but this method has limitations at low frequencies [11,14].…”