When it comes to wind farms, it may be the sound you can't hear that drives you to distraction, according to a report released this week that is pitting environmental groups against one another.
The study of noise levels around the Shirley Wind Farm in Brown County detected largely inaudible, low-frequency sound inside three nearby houses. But researchers found that only in the home closest to the turbines could it be correlated with sound coming from outside the house, according to the report released Monday.
The study concluded that between the low-frequency sound and the nausea, dizziness, headaches, ear pressure and other maladies reported by neighbors "enough evidence and hypotheses have been given herein to classify (low-frequency noise) as a serious issue, possibly affecting the future of the industry."
But the study could not conclude that the health problems reported by nearby residents were caused by the low-frequency sound from the eight-turbine project, according to Clean Wisconsin, a Madison environmental group that arranged the testing.
That's because "there aren't any documented peer-reviewed studies finding any health effects for inaudible sounds," said Tyson Cook, staff scientist for Clean Wisconsin, which favors development of renewable energy.
Duke Energy of Charlotte, N.C., which owns the Shirley Wind Farm, was reviewing the study but had no comment Thursday, spokesman Jason Walls said. Walls added that the facility was "in compliance with all laws and ordinances."
The study was paid for in part with funds awarded by the Public Service Commission to Clean Wisconsin and Forest Voice, a group of homeowners fighting the Highland Wind Farm, a proposed 41-turbine facility in St. Croix County. Both groups have been granted intervenor status in the Highland Wind Farm case before the PSC.
Two lawmakers and another group involved with the testing say the study could be groundbreaking.
"The report suggests that very low-frequency noise from wind turbines may cause motion sickness-like symptoms in some people," according to a statement from Forest Voice.
Rep. Andre Jacque, R-De Pere, called on the PSC to halt wind turbine construction "to keep this nightmare from spreading." Sen. Frank Lasee, R-De Pere, said in a statement the agency should "immediately establish new set-back requirements that protect the health and wellness of Wisconsin residents who are forced to live too close to these 500-foot-tall" industrial wind turbines.
The four companies in early December studied noise levels at three vacant houses near the Brown County wind farm as part of the hotly contested Highland proposal. The study detected low-frequency sound inside all three town of Glenmore homes, which had been vacated by owners complaining of negative impacts from the turbines.
One of the consultants, Robert Rand of Rand Acoustics in Brunswick, Maine, reported feeling nausea, headaches and dizziness after he spent long hours in the test homes. Rand, who suffers from seasickness, reported the symptoms subsided after about a week.
But only in the closest home, 1,280 feet from the turbines, was the low-frequency sound correlated with noise coming from the outside; state law requires a 1,250-foot separation between turbines and residences.
One of the consultants on the Shirley Wind Farm study, David Hessler of Hessler Associates Inc. of Haymarket, Va., said the study raises questions but offers no definitive answers.
"Nothing was actually discovered that would explain to any degree the health complaints reported by residents," Hessler said, adding that more testing is needed.
The report will be discussed at a Jan. 17 PSC hearing on the Highland application, which seeks permission for a 6,200-acre wind farm in the towns of Forest and Cylon in northeastern St. Croix County.