Collecting data on wind turbine sound to identify causes of identified concerns.

Abstract

Regulations for wind turbines are generally based on A‐weighted sound levels, and typical sound spectrums found in the community often from localized sources, such as an exhaust stack. The regulatory limits are generally at levels known to cause little annoyance in the community. Large industrial wind turbines with a sound emitter from 50 to 150 m overhead, and based on a source perhaps 100 m in diameter pose a relatively new source of sound to communities, particularly the rural communities where they are located. Community experience shows that the same A‐weighted sound limits that are acceptable for many typical sound spectrums and localized sources and pose a considerable level of annoyance for wind turbines. This paper sets out to identify the differences in the sound levels found at locations 500–600 m from wind turbines (about one‐third mile) considered acceptable by regulators near wind turbines, in both spectrum, intensity, duration, and special characteristics, such as tonality or amplitude modulation (cyclical pattern) compared to the sound levels at control sites distant by at least 5000 m (about 3 miles) from wind turbines. An explanation of the data collection method is given, as well as an analysis of extensive sound samples gathered.