The insertion loss of screens under the influence of wind

A hard screen on an absorbing ground is investigated experimentally and theoretically under the influence of wind. Upwind as well as downwind conditions are investigated. The experimental data are the result of model experiments in a 1:25 scale model within a wind tunnel. These experiments are meant to simulate the effect of noise screens located on outdoors surfaces such as grass covered ground. The sound propagation is measured using a triggered spark source and averaging on a power basis in the frequency domain. The meteorological data representing the wind conditions have been determined by means of hot-wire anemometry in positions on both sides of the screen as well as directly over the screen.The measured data are compared with calculated results obtained by means of parabolic equation methods. These calculations are based upon assumptions of laminar flow, but range dependent wind speed profiles are taken into account. The measurements are influenced by turbulence generated near the ground and additional turbulence generated by the screen. The influence of turbulence is discussed and interpreted. Additional calculations estimating the influence of turbulence when a screen is present are presented.