Limitations of the scattering coefficient for simulating early reflections

The Journal of the Acoustical Society of America, vol. 154, pp. A44

Abstract

The introduction of the scattering coefficient has enabled geometrically-based acoustic simulations to produce full-length impulse responses of fairly high accuracy. However, the scattering coefficient is a random-incidence quantity that can be applied only when considering a statistical energy average over different directions. This model is inaccurate if a single reflection by a surface element is considered for which the scattered part of the sound energy depends strongly on the angle of incidence. The resulting deviation can be particularly relevant for first-order reflections as these reflections have significant influence on acoustic parameters that make use of early-energy estimates, such as D, C80 or LF. In this paper, the uncertainty of the specularly reflected energy is estimated and discussed for a number of typical surface structures and scenarios. The corresponding impact on the accuracy of predicted early-energy parameters is also discussed. Possible solutions and extensions such as an angle-dependent scattering model are outlined.

Authors 3

1. Stefan Feistel
   Affiliation as printed

   AFMG, Berlin, Berlin, Germany

2. Michael Vorländer Aachen

   RWTH Aachen University

   Affiliation as printed

   IHTA, RWTH Aachen Univ., Aachen, Germany

3. Bruce C. Olson corresponding
   Affiliation as printed

   AFMG, Brooklyn Park, MN 55444, bruce.olson@afmg.eu