Sage Journals: Discover world-class research

Abstract

The neglection of diffraction is still a main problem of ray tracing in room and, even more, in city acoustics. The author's approach to diffraction is an energetic one based on the uncertainty relation (“the closer a sound particle passes an edge the stronger the diffraction effect”). In many numerical experiments, it has been validated quite well at the single screen as well as at the slit as reference cases, compared with Svensson's exact wave-theoretical secondary edge source model. To avoid an explosion of computation time due to the recursive split-up of rays, the long-term objective is to combine this diffraction method with Quantized Pyramidal Beam Tracing which allows a re-unification of beams. For preparation, the sound particle diffraction model has therefore been modified to the more efficient beam diffraction technique and with that has been tested for some additional configurations. Some improved by-pass-distance- and angle-dependent diffraction functions have been investigated. Also the reciprocity principle should be fulfilled. Recent experiments dealt with double diffraction, also at a cascade of two edges. Some new numerical results and comparisons with the reference model are reported. The further aim is to investigate the general applicability of the model to higher order diffraction.

Get full access to this article

View all access options for this article.

References

Stephenson

U. M.

, “Eine Schallteilchen-Computer-Simulation zur Berechnung der für die Hörsamkeit in Konzertsälen maßgebenden Parameter”, ACUSTICA 59 (1985), p. 1–20.

Vorländer

, “Simulation of the transient and steady-state sound propagation in rooms using a new combined ray-tracing image source algorithm”, J. Acoust. Soc. Am. 86, (1989).

Farina

, “a New Pyramid Tracer for Medium and Large Scale Acoustic Problems”, Proceedings of Euronoise (1995, Senlis, France).

Borish

, “Extension of the image model to arbitrary polyhedral”, J. Acoust. Soc. Am. 75, (1984).

Maekawa

, “Noise reduction by screens”, Applied Acoustics 1, (1968).

Kouyoumjian

R.G.

, and Pathak

P.H.

, “A Uniform Geometrical Theory of Diffraction for an Edge in a Perfectly Conduction Surface”, Proceedings of IEEE 62, (1974).

Tsingos

Funkhouser

Ngan

, and Carlbom

, “Modeling acoustics in virtual environments using the uniform theory of diffraction”, Proceedings of ACM Computer Graphics Siggraph, (2001).

Svensson

U. P.

, and Fred

R.I.

, “An analytic secondary source model of edge diffraction impulse responses”, J. Acoust. Soc. Am. 106, (1999).

Stephenson

U. M.

, and Mechel

F.P.

, “Wie werden Schallteilchen gebeugt?”, Proceedings of DAGA 1986 (Oldenburg).

10.

Freniere

E.R.

Gregory

G.G.

, and Hassler

R.A.

, “Edge diffraction in Monte Carlo ray tracing”, Optical Design and Analysis Software, Proceedings of SPIE, Denver, (1999).

11.

Stephenson

U.M.

, “Can also diffracted sound be handled as flow of particles? – Some new results of a beam tracing approach based on the uncertainty principle”, Proceedings of Acoustices joint SFA, EAA and ASA conference, Paris, (2008).

12.

Stephenson

U. M.

, “An Energetic Approach for the Simulation of Diffraction within ray Tracing based on the Uncertainty Relation”, ACUSTICA united with acta acustica, 96 (3) (2010) p. 516–535.

13.

Stephenson

U. M.

, “Quantized Pyramidal Beam Tracing – a new algorithm for room acoustics and noise immission prognosis”, ACUSTICA united with acta acustica 82, (1996).

14.

Stephenson

U. M.

, “Quantized Pyramidal BeamTracing or a Sound-Particle-Radiosity-Algorithm? – New solutions for the simulation of diffraction without explosion of computation time”, Proceedings of research symposium (Inst. of Acoustics, Salford, 2003).

15.

Pohl

, and Stephenson

U. M.

, “From ray to beam tracing and diffraction – an analytical prognosis formula for the trade-off between accuracy and computation time”, Proceedings of DAGA 2010 (Berlin).

16.

Pohl

, and Stephenson;

U. M.

“A combination of the sound particle simulation method and the radiosity method”, Proceedings of ISRA, Melbourne 2010.

17.

Pohl

, and Stephenson

U. M.

, “Efficient simulation of sound propagation including multiple diffractions in urban geometries by convex sub-division”, Proceedings of Internoise 2010 Lisbon.

18.

Pierce

A. D.

, Acoustics- an Introduction to its Physical Principles and Applications , Acoust. Soc. of. Am., 2^nd print, 1991.

Introducing Higher Order Diffraction into Beam Tracing Based on the Uncertainty Relation

Abstract

Get full access to this article

References