Potentially harmful noise from wind farms can be detected up to 3.5km from the nearest turbine and is present for 16 per cent of the time, a study has found.
A group of volunteers is presently undergoing laboratory tests at Flinders University in South Australia as researchers zero in on the little-studied amplitude modulation as a possible cause of complaints about sleep disturbance and other health effects from wind turbine noise.
Amplitude modulation is described as “thumping” or “rumbling” and is related to the frequency of turbine blades passing the tower and power outputs of wind turbines.
The National Health and Medical Research Council has funded a series of studies into wind farm noise following complaints from nearby residents.
Earlier studies of scientific literature by the council found little quality research had been done. Since the council study was announced, the World Health Organisation has added wind turbine noise as a source of potential health impacts above certain levels.
An update on the Australian research released yesterday by Flinders University said while effects of wind turbine noise on sleep were still being investigated, amplitude modulation (AM) was one of the most prominent features of wind turbine noise.
Results of the investigation were published in Journal of Sound and Vibration (Elsevier).
“In this first study, we found that audible AM decreases with distance from the wind farm but still remained prominent over long distances,” Dr Kristy Hansen, the leader of the Flinders research team said.
“The prevalence of AM has not been widely reported either in Australia or worldwide, although it’s well known that it results in increased annoyance in listening tests — and has also been cited in complaints from residents living near wind farms,” Dr Hansen said.