Recent advancements in the wind turbine technology, combined with available federal and state incentives, have greatly enhanced the development of wind powered electric generation facilities in the Eastern United States. Particularly ridges of the Allegany Mountains in New York, Pennsylvania, Maryland, West Virginia, and Virginia have become attractive sites for commercial wind farm developers. The fast development of commercial wind farms is currently an important issue in these regions due to environmental impacts.
The paper describes the demographic structure of the Allegany Mountains and presents an assessment of the audible noise at residences near actual wind turbines. The noise level recommendations of the USA Environmental Protection Agency (US-EPA) and local noise ordinances that apply to wind turbines are compared with the acceptable noise levels in various countries. The current status and trend of the wind power development in the Eastern USA, the expected benefits, and public concerns are discussed.
Sound generated by wind turbines had particular characteristics and it creates a different type of nuisance compared to usual urban, industrial, or commercial noise. The interaction of the blades with air turbulences around the towers creates low frequency and infrasound components, which modulate the broadband noise and create fluctuations of sound level. The low frequency fluctuations of the noise is described as "swishing" or "whooshing" sound, creating an additional disturbance due to the periodic and rhythmic characteristics.
The set of permissible limits for windmill noise that can be uniformly applicable over the nation is not available in the USA. Instead of imposing standard noise limits, the US Environmental Agency (US-EPA) suggests local governments developing their own noise regulations or zoning ordinances. Many countries developed national noise limits applicable to wind turbines.
Specific noise limits need to be developed by considering the characteristics of wind turbine noise. Especially the low frequency sound components and the modulation of the background noise resulting must be considered to represent the activity interference of the wind turbine sound. Adequate criteria to assess the wind turbine sound will greatly help the development of the wind industry by reducing the community reaction based on subjective opinions.