Interlaboratory Comparison and Analysis of Bidirectional Scattering Coefficients for Various Surfaces

Acta Acustica, vol. 10, pp. 65

Abstract

Accurate modeling of acoustic scattering is essential for realistic sound-propagation simulations in architectural environments. Traditional random-incidence models fail to represent directional scattering from structured surfaces, motivating the need for detailed bidirectional datasets. A reproducibility analysis of random-incidence and bidirectional scattering coefficient (BSC) measurements was conducted across two laboratories (RWTH Aachen University and The University of Sydney) using different free-field setups and two control surfaces–a 1D-sinusoidal and a 2D-rectangular profile. Measurements were compared with diffuse-field measurements (ISO 17497-1) and numerical simulations replicating the physical setups. Both laboratories produced consistent random-incidence scattering coefficients and BSCs for the 1D-sinusoidal surface. The 2D-rectangular surface showed larger deviations, attributed to edge effects and setup differences. Additional surfaces–including singular objects, random and modular geometries, and small-scale building façade elements–were measured or simulated. The method reliably captures directional scattering across various surface types. Setup geometry, edge effects, and signal-to-noise ratio were identified as key accuracy factors. The resulting coefficients together with its surface and setup descriptions provide a standardized foundation for future acoustic simulations and architectural applications.

Authors 7

1. Anne Heimes Aachen Institute for Hearing Technology and Acoustics

   RWTH Aachen University

   Affiliation as printed

   Institute for Hearing Technology and Acoustics, RWTH Aachen University

2. Densil A. Cabrera

   The University of Sydney

   Affiliation as printed

   School of Architecture, Design and Planning, The University of Sydney

3. Jonothan Holmes

   The University of Sydney

   Affiliation as printed

   School of Architecture, Design and Planning, The University of Sydney

4. Dagmar Reinhardt

   The University of Sydney

   Affiliation as printed

   School of Architecture, Design and Planning, The University of Sydney

5. Iremnur Tokac Celikyay Aachen Individualized Production (IP)

   RWTH Aachen University

   Affiliation as printed

   Individualized Production, RWTH Aachen University

6. Sigrid Brell‐Çokcan Aachen Individualized Production (IP)

   RWTH Aachen University

   Affiliation as printed

   Individualized Production, RWTH Aachen University

7. Michael Vorländer Aachen Institute for Hearing Technology and Acoustics

   RWTH Aachen University

   Affiliation as printed

   Institute for Hearing Technology and Acoustics, RWTH Aachen University