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The leading international wind energy expo is the meeting place for onshore and offshore experts from all around the world. Make the most of WindEnergy Hamburg: For your business – back up your success For your market insights – get  rst-hand up-to-date information For more power to your network – develop, widen and maintain your business contacts Plan your visit to WindEnergy Hamburg now. Be there when we open your gateway to the world of wind energy, in the vibrant city of Hamburg from September 23 to 26, 2014. Wind Edition Enercon turbines in the wind farm at Wilstedt in Lower Saxony. At a maximum of 33 dBA, the wind farm is well within legal noise levels, and yet the AM phenomenon is causing annoyance. Over the course of two years, 212 local residents were therefore interviewed, and their responses compared with those from residents near another 13 wind farms. In the first round, 30 % of those interviewed were not at all bothered by the wind farm, 25 % felt somewhat bothered and 10  % were very disturbed. The latter had trouble sleeping and struggled with negative moods. After the first round of interviews, the turbines were run in various modes over a period of six months and a selection of residents regularly questioned. The results were baffling: “Changing the operational parameters had absolutely no effect. There was neither a linear nor systematic development. We had expected a positive effect. Also, the distance to the turbines made no difference whatsoever. The same was found in samples from other sites”, explains Project Manager Johannes Pohl, a psychologist at the University of Halle-Wittenberg. A matter of habituation The results of the second round of interviews were just as puzzling. This time the researchers included the nuisance from traffic. Only 7 % of respondents still felt very disturbed by the wind farm, but 16 % were very disturbed by the traffic in Wilstedt. According to the psychologist, “it seems that most people can deal with the noises better over time. So the operation of the wind farm has a positive effect in the longer term.” He offers an explanation: “The higher values at the start of the study could be related to the fact that the planning and construction phase had led to an extended period of stress.” Despite this, he warns against ignoring the health effects on the minority who still feel bothered by the noise. This view is shared by Joachim Gabriel, noise assessor at the German Wind Energy Institute, who was in charge of the measurements for the study at the wind farm and at the inhabitants’ houses. “Wilstedt is not an isolated case. The same phenomenon appears at other wind farms. That is why it is important to develop a standardised method for measuring amplitude modulation. This would give us a tool for long-term measurements”. The manufacturers are also working on identifying the causes of the problem. “We take the complaints very seriously and are working to get to the bottom of the phenomenon”, explains Felix Rehwald, press spokesperson for Enercon. He believes that in addition to long-term studies, continual noise measurements at the turbines could be helpful. There would be more objective data to go by instead of subjective assessments. Torsten Thomas


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