Sounds created by wind turbines operating in rural areas can vary from inaudible to neutral to unhealthy, depending on wind, weather and terrain and the distance from a residence, according to an expert who spoke this week to a crowd of about 75 municipal officials and residents meeting in Allegany.
Charles Ebbing, an acoustics expert who is working with a committee on a wind farm proposal in the northern New York community of Orleans, was invited to speak at a meeting of the Allegany Town Planning Board. The board held the meeting at the request of a group of residents in the Chipmonk area of Allegany, a neighborhood that has been chosen by Everpower Renewables for its 32 -turbine wind energy conversion project.
Ebbing said he is not for or against wind energy but cautioned town officials to set noise guidelines for the project after obtaining independent readings of ambient sound levels from at least 20 different locations at different times of day and in different seasons. He warned that turbine noises are magnified during temperature inversions and will be heard at greater distances if the community's ambient readings are at or below the 25 or 30 decibels prevalent in rural areas.
"The people you are killing are the people that are in the pristine environments," he said, noting that most rural residents don't use air-conditioners that could mask some noise and are in the habit of keeping their windows open at night when turbine noise is the loudest.
Ebbing cited numerous scientific studies of different types of sound, especially those that have helped mitigate unwanted noise from industrial machinery and heating and air conditioning systems.
He also described the effects of infrasound, inaudible to humans at frequencies below 20 cycles per second, that cause the cells to shake and produce a collagen that stiffens the arteries. "There are enough red flags about infrasound that it ought to be checked out," Ebbing told the group, which included elected officials from several other towns in the region faced with wind energy projects.
Placement of the turbines can make a difference in noise levels. The sound sometimes cannot be heard directly beneath the turbines, depending on the terrain, while it might be loud some distance away. Also, he said, sounds can spill into a valley and will stay within the valley, getting louder as they bounce off surfaces.
"You need to analyze real world results," Ebbing said, adding that he knows of only one wind energy project that has been measured for noise.
After the presentation, Everpower Development Director Kevin Sheen said the company has already conducted a preliminary sound assessment and will soon submit a noise study to the Planning Board.
Planning Board officials said the presentation will be used as background, but it is too early to evaluate noise issues.
The board will meet again at 7 p.m. Monday in the Town Hall conference room, 52 W. Main St.