Abstract
Simulations based on the concepts of geometrical acoustics are today well-established tools for acousticians, being widely used for evaluation of sound quality in rooms and urban spaces. However, although a lot of different models are available and have been evaluated in the past, it is still very important to guarantee the validity and quality of simulated data and reproduced sound. This work presents a comparison between the signal processing strategies in two acoustic simulators based on geometrical models. Obvious expectation was that both simulators would produce the same results when fed by exactly the same input data. However, issues related to model assumptions, propagation methods characteristics and signal processing techniques adopted by each simulator introduce differences which alter the final results, i.e., the simulated acoustic impulse responses. This papers aims to present such deviation and helps to understand the influence of each component over the results. Firstly, both simulators are described in detail, presenting their acoustic models and the signal processing approaches. In addition, an extensive analysis of early reflections is performed, considering pressure levels, reflection order, their arrival time and directional characteristics. Next, simulated energy decay curves, monaural room acoustic parameters and spectra are objectively compared to measured data of a reverberant chamber, in two different conditions. The differences are then pointed out and minimized by unifying the signal processing of both simulators. The results of this comparison reveal that signal processing and inherit method characteristics still have strong influence over the simulated impulse responses, mainly for the late part. Some consequences are energy misbalance between early and late parts of impulse response, leading to differences over the room acoustic parameters, mainly clarity and definition.
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References
Savioja L, Svensson UP (2015) Overview of geometrical room acoustic modeling techniques. J Acoust Soc Am 138:708
Allen JB, Berkley DA (1979) Image method for efficiently simulating small-room acoustics. J Acoust Soc Am 65:943–950
Kéan C, Xiangyang Z, Jincai S (2003) On the accuracy of the ray-tracing algorithms based on various sound receiver models. Appl Acoust 64:433–441
Immel DS, Cohen MF, Greenberg DP (1986) A radiosity method for non-diffuse environments. ACM SIGGRAPH Comput Graph 20(4):133–142
Koutsouris G, Brunskog J, Jeong C-H, Jacobsen F (2013) Combination of acoustical radiosity and the image source method. J Acoust Soc Am 133(6):3963–3974
Pohl A, Stephenson U (2014) Combining higher order reflections with diffractions without explosion of computation time: The sound particle radiosity method. In: EAA Joint Symposium on Auralization Ambisonics, Berlin, Germany
Mommertz E (1996) Untersuchung akustischer Wandeigenschaften und Modellierung der Schallrückwürfe in der binauralen Raumsimulation. PhD Thesis. PhD thesis, RWTH Aachen University, Germany
ISO 3382-1 (2009) Acoustics – Measurement of room acoustic parameters–Part 1: Performance spaces (2009-06-15). International Organization for Standardization, Switzerland
Katz BFG (2004) International round robin on room acoustical impulse response analysis software 2004. Acoust Res Lett Online 5(4):158. https://doi.org/10.1121/1.1758239
Stephenson U (1990) Comparison of the mirror image source method and the sound particle simulation method. Appl Acoust 29(1):35–72
Bork I (2000) A comparison of room simulation software? The 2nd round robin on room acoustical computer simulation. Acta Acustica 86(6):943–956
Bork I (2005) Report on the 3rd round robin on room acoustical computer simulation? Part II: Calculations. Acta Acustica 91(4):753–763
Tenenbaum RA, Camilo TS, Torres JCB, Gerges SNY (2007) Hybrid method for numerical simulation of room acoustics with auralization: part 1—theoretical and numerical aspects. J Braz Soc Mech Sci Eng 29:211–221
Krokstad A, Strm S, Srsdal S (1983) Fifteen years éxperience with computerized ray tracing. Appl Acoust 16(4):291–312
Pelzer S, Aspöck L, Schöder D, Vorländer M (2014) Integrating real-time room acoustics simulation into a cad modeling software to enhance the architectural design process. Build Open Access J 2:113–138
Schröder D (2011) Physically based real-time auralization of interactive virtual environments. PhD thesis, RWTH Aachen University, Germany
Strom S, Krokstad A, Sorsdal S (1968) Calculating the acoustical room response by the use of a ray tracing technique. J Sound Vib 8(1):18–25
Lewers T (1993) A combined beam tracing and radiant exchange computer model of room acoustics. Appl Acoust 38:161–178
Schröder D, Vorländer M (2011) Raven: A real-time framework for the auralization of interactive virtual environments. Acta acustica united with Acustica 97(S1):1541–1546
Leopardi P (2007) Distributing points on the sphere: Partitions, separation, quadrature and energy. PhD thesis, The University of New South Wales, School of Mathematics and Statistics, Australia
Pelzer S, Schröder D, Vorländer M (2011) The number of necessary rays in geometrically based simulations using the diffuse rain technique. In: Proceedings of DAGA 2011, Düsseldorf, Germany
Heinz R (1994) Entwicklung und Beurteilung von computergestützten Methoden zur binauralen Raumsimulation. PhD thesis, RWTH Aachen University, Germany
Aspöck L, Pelzer S, Vorländer M (2014) Using spatial information for the synthesis of the diffuse part of a binaural room impulse response. In: Proceedings of DAGA 2014, Oldenburg, Germany
OpenDaff. Directional Audio File Format. www.opendaff.org. Accessed 18 May 2018
Aretz M (2012) Combined wave and ray based room acoustic simulations of small rooms. PhD thesis, RWTH Aachen University, Berlin, Germany
Pelzer S, Aretz M, Vorländer M (2011) Quality assessment of room acoustic simulation tools by comparing binaural measurements and simulations in an optimized test scenario. Forum Acusticum 2011: 27 June–01 July, Aalborg, Denmark
Jeong CH (2012) Absorption and impedance boundary conditions for phased geometrical-acoustics methods. J Acoust Soc Am 132(4):2347–2358
Boucher M (2017) Phased geometrical acoustics using low/high frequency reflection coefficients with applications to absorption measurements. PhD Thesis, University of Leuven, Department of Mechanical Engineering, UK
Rindel JH (1993) Modelling the angle-dependent pressure reflection factor. Appl Acoust 38(2–4):223–234
Lindau A, Erbes V, Lepa S, Maempel H, Brinkman F, Weinzierl S (2014) A spatial audio quality inventory (SAQI). Acta acustica united with Acustica 100:984–994
Vorländer M (2014) Simulation and evaluation of acoustic environments. Build Acoust 21:11–20
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This study was supported by the Brazilian and German research founding agencies CAPES and DAAD.
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Technical Editor: Wallace Moreira Bessa.
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Torres, J.C.B., Aspöck, L. & Vorländer, M. Comparative study of two geometrical acoustic simulation models. J Braz. Soc. Mech. Sci. Eng. 40, 300 (2018). https://doi.org/10.1007/s40430-018-1226-1
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DOI: https://doi.org/10.1007/s40430-018-1226-1