A transient boundary element method model of Schroeder diffuser scattering using well mouth impedance

Hargreaves, JA; Cox, TJ

Abstract

Room acoustic diffusers can be used to treat critical listening environments to improve sound quality. One popular class is Schroeder diffusers, which comprise wells of varying depth separated by thin fins. This paper concerns a new approach to enable the modelling of these complex surfaces in the time domain. Mostly, diffuser scattering is predicted using steady-state, single frequency methods. A popular approach is to use a frequency domain Boundary Element Method (BEM) model of a box containing the diffuser, where the mouth of each well is replaced by a compliant surface with appropriate surface impedance. The best way of representing compliant surfaces in time domain prediction models, such as the transient BEM is, however, currently unresolved. A representation based on surface impedance yields convolution kernels which involve future sound, so is not compatible with the current generation of time-marching transient BEM solvers. Consequently, this paper proposes the use of a surface reflection kernel for modelling well behaviour and this is tested in a time domain BEM implementation. The new algorithm is verified on two surfaces including a Schroeder diffuser model and accurate results are obtained. It is hoped that this representation may be extended to arbitrary compliant locally reacting materials.

Citation

Hargreaves, J., & Cox, T. (2008). A transient boundary element method model of Schroeder diffuser scattering using well mouth impedance. ˜The œJournal of the Acoustical Society of America (Online), 124(5), 2942-2951. https://doi.org/10.1121/1.2982420

• Journal Article Type: Article
• Publication Date: Nov 1, 2008
• Deposit Date: Apr 13, 2011
• Publicly Available Date: Apr 5, 2016
• Journal: The Journal of the Acoustical Society of America (JASA)
• Print ISSN: 0001-4966
• Peer Reviewed: Peer Reviewed
• Volume: 124
• Issue: 5
• Pages: 2942-2951
• DOI: https://doi.org/10.1121/1.2982420
• Publisher URL: http://dx.doi.org/10.1121/1.2982420