The bad news for windfarms is that the noise they produce can disrupt sleep.

The good news is that they are no more likely to wake people from their slumber than road traffic.

That’s the findings of a team of South Australian researchers who presented their study into windfarm noise at an international conference earlier this month.

Chief investigator Professor Peter Catcheside, a sleep physiologist from Flinders University in Adelaide, says the rapid expansion of wind farms in Australia and overseas has been associated with a range of community complaints and concerns, including noise impacts on sleep.

“They do make noise, they’re a very large machines that generate low frequency noise that can transmit very long distances and penetrate into buildings more readily than high frequency,” he told Government News.

“Because of community complaints and concerns for that noise to impact sleep we thought it was important to do a study and really look at the impact of wind farm noise on sleep.”

Loud traffic noise more disruptive

The team has been studying the impact of exposure to wind farm noise during sleep on a five-year research grant and produced more than 20 papers.

In their latest study, 20-second recordings of wind farms, gathered during field trips, and road traffic noise samples from a busy main road in suburban Adelaide were played at different noise levels while participants slept.

The study then tested if three-minute noise samples, including very low-frequency wind farm infrasound alone, resulted in sleep disturbance.

“Basically we didn’t find too many differences between the two noise types,” Professor Catcheside said. “If anything the loudest road traffic noise that we played was a little bit more sleep disruptive than windfarm noise at the same loudness level.”

The researchers also found that wind farm infrasound – or sounds below the lower limit of human audibility – was not audible to the human ear during wakefulness, and produced no evidence of sleep disruption.

“Our results align with previous studies and showed that infrasound played at realistic levels was not audible during wakefulness,” he said.

“Infrasound is therefore unlikely to explain noise complaints from wind farms, suggesting that other low frequency audible rumbling and thumping components deserve more attention towards better understanding wind farm noise effects on sleep.”

Realistic expectations

Professor Catcheside says the study underscores the need for local authorities that are supporting new or existing wind farms to engage with their community.

You need to negotiate with the community about something coming into their area which will make some noise and reassure them that yes, it does make noise, and it’s low frequency, so it can go long distances, but we haven’t found any evidence that wind farm noise is much different from other noise types and it’s relatively quiet.

Professor Catcheside

“You need to negotiate with the community about something coming into their area which will make some noise and reassure them that yes, it does make noise, and it’s low frequency, so it can go long distances, but we haven’t found any evidence that wind farm noise is much different from other noise types and it’s relatively quiet,” he says.

He says while there’s a lot of engineering going on to ensure wind farms make as little noise as possible, it’s unlikely they will ever be completely silent.

“They’ve got gear boxes and they make a fair amount of noise from turbulence effects and from the blade passing the tower,” he says.

“Noise is a problem for the industry. If you could make the perfect machine which is completely quiet they would be very happy.”

The yet-to-be-published findings were presented at the International conference on Wind Farm Noise in Dublin on June 22 .