Paper

“A Framework for the development of accurate acoustic calculations for games”

Authors

Panagiotis Charalampous, Panos Economou

Abstract

 Despite the rapid development in acoustics calculation software during the last couple of decades, such advances have not been achieved uniformly. Various demands in different disciplines have shifted the focus to a number of different aspects of the calculations. Methods in game development have focused on speed and optimized calculation times to achieve interactive sound rendering, whilst engineering methods have concentrated in achieving accuracy for reliable predictions. This paper presents a flexible, expandable and adjustable framework for the development of fast and accurate acoustics calculations both for game development and engineering purposes. It decomposes the process of acoustic calculations for 3D environments into distinct calculation steps and allows third party users to adjust calculation methodologies according to their needs.

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Paper

“A comparison of ISO 9613 and advanced calculation methods using Olive Tree Lab-Terrain, an outdoor sound propagation software application: Predictions versus experimental results”

Authors

Panos Economou, Panagiotis Charalampous

Abstract

The process of performing an Environmental Impact Assessment includes the study of noise propagation. Often, the path from a noise source to a noise sensitive location involves complicated mechanisms of sound transmission. These mechanisms may relate to diffraction & reflections from obstacles (natural or man made), ground properties, and meteorological conditions. The International Standards Organization proposes with standard ISO9613-2, methods by which to calculate these effects. While they are relatively easy to implement, they underestimate the true workings of the aforementioned mechanisms. In this paper, we present the OTL - Terrain software application, which accurately and precisely simulates outdoor sound propagation. The software application can be used for the prediction of environmental noise and the design of control measures. OTL - Terrain is an application which uses geometrical acoustics (GA) and models the propagation of sound in terms of rays. The tool makes use of the image source method (ISM) combined with visibility tracing techniques to implement a novel method of path-detection, taking both reflection and diffraction effects into account. Calculations utilize the predicted reflections from finite-sized objects with Fresnel zone corrections,  an unlimited order of diffraction, and atmospheric turbulence. This paper presents a comparison of the predictions made by the OTL – Terrain application, the methods proposed by ISO, and the published results from experimental data.

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Panos Economou, Panagiotis Charalampous, Stefanos Ioannides, Polykarpos Polykarpou

This paper examines the effect of sound diffraction in predicting sound propagation in ancient theatres. Few simulation studies to date concerning ancient theatre acoustics were conducted with diffraction effects. While sound diffraction effects in ancient theatres are known qualitatively, rarely have they been quantitatively documented. In this paper, the ancient theatre of Kourion in Cyprus was acoustically modeled and simulated, in a commercially available software application which handles also sound diffraction to high orders. Sound measurements were also taken at the theatre for comparison purposes. All analyses were conducted in the frequency domain. Comparison of results of the variation of sound pressure level with distance and frequency shows that the contribution of sound diffraction is significant. It is proposed that future acoustical simulations of ancient theatres should include sound diffraction effects.

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