Panos Economou

Bio: Panos Economou is an academic researcher. The author has contributed to research in topics: Standardization. The author has an hindex of 1, co-authored 2 publications receiving 2 citations.

A comparison of ISO 9613-2 and advanced calculation methods: Predictions versus experimental results

Abstract: Standardization provides methodologies by which independent investigations of the same situation are able to derive the same conclusions. However, standardization is sometimes also perceived as absolute and accurate, beyond which one should not investigate matters deeper. The responsibility of the accuracy of these methods does not lie with the developers but with the standards organizations. This is not the case with algorithms based on pure scientific research where the full responsibility lies with those who turn it into software applications. The Simulation and prediction of outdoor sound propagation using advanced calculation methods are based on principles of physics with an effort to try to avoid empirical or approximate methods, often found in published outdoor propagation standards.

Versus experimental results

Abstract: 1 i n t r o d u c t i o n Standardization provides methodologies by which independent investigations of the same situation are able to derive the same conclusions. However, standardization is sometimes also perceived as absolute and accurate, beyond which one should not investigate matters deeper. Moreover, often enough the engineering community tends to neglect the science (or lack of it) underlying standardized methods and just follows prescriptions. Standardization provides algorithms that can be turned into software code. Software developers are always looking for ready-made algorithms with great market potential. The responsibility of the accuracy of these methods does not lie with the developers but with the standards organizations. This is not the case with algorithms based on pure scientific research where the full responsibility lies with those who turn it into software applications. Faced with a choice between prescribed methods of standardization with simple mathematical code vs. accurate scientific findings, PEMARD applied the latter developing complicated mathematical computation, albeit slower, yet delivering more accurate results in its commercially available software application1. 2 c o m m e r c i a l l y a v a i l a b l e t h e o r e t i c a l l y b a s e d s o f t w a r e a p p l i c a t i o n t h e o r e t i c a l b a c k g r o u n d The Simulation and prediction of outdoor sound propagation using advanced calculation methods are based on principles of physics with an effort to try to avoid empirical or approximate methods, often found in published outdoor propagation standards. The commercially available software application, utilizes sound ray modeling which solves Helmholtz’s sound wave equation, accounting for sound diffraction to any order, sound wave reflection from finite size surfaces of finite impedance using Fresnel Zones and spherical wave reflection coefficient concepts, respectively. The approach uses flow resistivity instead of sound absorption coefficient. It also takes into account geometrical spreading, atmospheric absorption, and atmospheric turbulence. The software application also has an in-house developed algorithm to detect valid diffraction and reflection sound paths from source to receiver in a proper 3D environment. It is based on the image source method and the Geometrical Theory of Diffraction according to Keller2. 3 ISO 9613-23 BACKGROUND

Sound propagation in 3D spaces using computer graphics techniques

Abstract: Sound propagation in 3D spaces is governed by similar physical principles as light. As a result, sound rendering in a 3D virtual environment can benefit from methods developed for graphics rendering and vice versa. In this review, we provide an overview of methods used for sound rendering that share concepts and techniques with graphics rendering. Firstly we describe geometrical propagation techniques where the computations are based on ray theory similar to ray tracing techniques in computer graphics. Secondly, we review numerical techniques. These techniques, similar to the idea of radiosity, are based on the subdivision of the space into elements. Then we describe acceleration techniques that can be used in combination with other methods to speed up calculations. Lastly, for the sake of completeness, a quick overview is given of sound computation techniques that simulate specific sound effects that do not apply on illumination. The aim of this survey is to share knowledge among the two disciplines using familiar and known concepts.