10 th Convention of the European Acoustics Association Turin, Italy • 11 th – 15 th September 2023 • Politecnico di Torino MODEL FOR SOUND PROPAGATION CONSIDERING METEOROLOGICAL CONDITIONS Dieter Hohenwarter 1*1 Erich Mursch-Radlgruber 2 Christian Kirisits 3 1 TGM -Institute of Technology, Department for Research and Testing, A 1200 Vienna, Wexstrasse 19-23, Austrian 2 University of Natural Resources and Life Sciences Vienna (BOKU), Institute of Meteorology (BOKU-Met), A 1180 Vienna, Gregor-Mendel-Strasse 33, Austria 3 Kiristis Consulting Engineers and Medical University of Vienna, Department of Radiation Oncology, A 1090 Vienna, Waehringer Gürtel 18-20 ABSTRACT * For acoustic measurements of more than about 100 m distance, the meteorological effects have an increasing influence with increasing distance. The sound level differences between a reference point close to the passing vehicles and at distances of 100 m to 500 m from motorways and railway tracks were determined. Here the influence of meteorology is described by the effective gradient of the sound velocity c' eff determined from the measured temperature and vector wind speed gradients. It is shown that c' eff and the level difference correlate very well. The correlation can be approximated by an S-Function which is constant for large positive or negative gradients of the effective sound speed. The acoustic influences of downwind and upwind are also shown as a function of frequency. Keywords: Sound propagation, Meteorology, Effective sound speed gradient, S-shaped sound level attenuation 1. INTRODUCTION For traceable noise measurements from 100 m distance from the sound source, the meteorological conditions must be ————————— 1 * Corresponding author: dhohenwarter@tgm.ac.at Copyright: ©2023 Dieter Hohenwarter et al. This is an open-access article distributed under the terms of the Creative Commons Attribu- tion 3.0 Unported License, which permits unrestricted use, distribu- tion, and reproduction in any medium, provided the original author and source are credited. documented. The very important book "Predicting Outdoor Sound" by Keith Attenborough and Thimothy van Renterghem includes in the first chapter the influence of meteorological conditions on sound propagation [1]. Measured effects of the atmospheric boundary layer on the sound propagation determined during the period from the early evening to the next day are presented in Ref. [2]. In particular, the measured height-dependent temperature and wind speed distributions are compared with the results of log-linear profiles as they are also commonly used for sound propagation calculations. 2. MEASUREMENT AT DIFFERENT LOCATIONS AND CALCULATION OF THE EFFECTIVE SOUND SPEED GRADIENT Acoustic measurements were made close to the highway or railroad and at a distance of 100 to 500 m from the sound source to determine the influence of meteorological conditions on sound propagation. In all cases, meteorological measurements were carried out with a tower of at least 10 m, where the wind speed and direction together with the air temperature were recorded continuously at different heights (temperature at 0.3 m, 2 m, 5 m and 10 m, wind speed and direction at 2 m, 5 m and DOI: 10.61782/fa.2023.0165 5513