Directional processing in assessment of wind turbine noise

Abstract

Assessments of wind turbine generator (WTG) noise are required to comply with the US Environmental Agency and local governments and avoid legal action that may result of non-compliant operation. Current methods for WTG noise measurements require the comparison of long-term sound data recorded before and after a WTG installation. These measurements must be conducted during several months for various wind speeds and environmental conditions. Such measurements are complicated due to the presence of multiple sources other than noise not from WTG, including intermittent and fluctuating sources. The application of directional processing can help localize and identify the sources responsible for increased sound levels at any given moment and to estimate the contribution of the other than WTG sources to the whole sound level. Stevens has developed various acoustic systems with several sensors that provide directional processing of sounds that were previously applied for detection, tracking and classification of small boats, divers, small aircraft, and drones. We propose modifications of such systems for directional sensing of WTG noise at long distances in the frequency band relevant for WTG noise measurement.