Rumbling wind farm noise can be persistent enough to annoy residents 3.5km away, and can be detected at a range of nearly 9km, a Flinders University study has found.
Researchers took readings at nine properties at various distances from the Waterloo Wind Farm, east of the Clare Valley.
They were all homes where residents had complained about noise disturbing their sleep.
The thumping or rumbling noise related to the frequency of turbine blades passing the towers, and the turbine power output, was audible indoors up to 3.5km away for 16 per cent of the time overall, and 22 per cent of the time at night. Such noise, known as amplitude modulation (AM), was audible for 20 per cent of the time at a 2.4km distance, but was only detected once over the range of 7.6-8.8km.
The study is the start of an ongoing project to determine the effects of wind turbine noise on sleep.
“In this first study, we found that audible AM decreases with distance from the wind farm but still remained prominent over long distances,” study leader Dr Kristy Hansen 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.”
Noise recordings were similar for wind farm power outputs of between 40 and 85 per cent.
“This indicates that it is important that AM analysis is not restricted to high power output conditions only,” Dr Hansen said.
Another recent Flinders University paper found that vibrations from wind farms, as opposed to noise, were unlikely to cause problems for residents over distances of 2.4km, 3.3km and 5km.
Flinders sleep expert Professor Peter Catcheside, pictured, said for the broader project, the field work was done but more analysis was needed on the sleep effects.
“Based on our noise studies in the field, we will faithfully reproduce key elements of wind farm noise for direct comparison against quiet periods and traffic noise in both daytime listening tests and overnight sleep studies,” he said. “These studies will map out the dose-response effects of wind turbine noise compared to better known traffic noise effects on sleep.”