The noise from wind farms is no more disruptive to sleep than road traffic, researchers have found.
Campaigners have previously claimed that low-frequency noises – including ‘infrasound’, or below our hearing range – affect human sleep.
Now scientists have analysed 460 sleep nights with 68 participants over five years.
The study by Flinders University in Adelaide, South Australia, found that wind farm noise disrupted sleep about the same as road traffic.
The researchers said the very low-frequency wind farm noise was not audible to the human ear, whether participants were awake or asleep.
Volunteers spent seven nights in a sleep laboratory and were recruited from groups including those near wind farms and those near busy suburban roads.
The volunteers played 20-second noise samples of the wind farm and road traffic noise at different sound pressure levels.
Wind Farm Noise and Public Perception
The researchers found that exposure to either wind farm or road traffic noise triggered a slight increase in the number of people waking up, which could lead to disrupted sleep.
Chief investigator Peter Catcheside said the study showed that loud noises from either wind farms or traffic could disrupt sleep.
He said: “At realistic levels, these effects were relatively small.
“We also found no evidence to suggest that wind farm noise is more disruptive to sleep than road traffic noise.
“At the highest exposure level, road traffic noise was a little more sleep disruptive than wind farm noise.”
New research has put to bed the repeated claims from some wind farm opponents that wind farms affect sleep from audible noise or infra-sound.
Two papers from Flinders University researchers found that noise from wind farms does not affect sleep more than traffic noises, and ‘realistic’ levels of very low-frequency sound or infrasound can neither be heard by sleepers nor causes any signals in the brain.
While both wind farm noise and road traffic noise disrupt sleep a little, it depends on noise loudness and sleep depth at the time of noise exposure.
Flinders University sleep expert and chief investigator Professor Peter Catcheside said that at its noisiest, road traffic noise was a bit of sleep disruptive than wind farm noise.
When infrasound was played, the lack of brain activity indicates that it’s unlikely to be behind noise complaints from wind farms.
“It suggests that other low-frequency audible rumbling and thumping components deserve more attention towards better understanding wind farm noise effects on sleep,” he said.
The papers were presented at the International Conference on Wind Farm Noise in Dublin, and while the data is still peer-reviewed, it builds on a growing body of research that indicates wind farm noise doesn’t affect sleep.
In March, a similar study was published by sleep researchers at the Woolcock Institute, which looked at the health effects of infrasound and wind farm noise. It found no effect from three days of infrasound exposure to various health indications, from sleep, blood pressure, balance and hearing.
The two new Flinders University papers are part of a five-year study and showed that short exposure to the wind farm and road traffic noises wakes a small number of people. Very low-frequency infrasound produced no evidence of sleep disruption.
Implications for Wind Farm Development
The project involved over 460 sleep study nights from 68 participants. It included people living near a wind farm with and without noise-related sleep difficulties, residents living near a busy suburban road and people living in quiet rural areas, who spent seven consecutive nights in the sleep laboratory.
The road noise study repeatedly played 20-second wind farm and road traffic noise samples during participants’ sleep using three different sound pressure levels to compare their sleep disruption responses between the two different noise types.
On a different night, the study tested if longer three-minute noise samples, including very low-frequency wind farm infrasound alone, resulted in sleep disturbance.
The studies used noise samples captured from long-term measurements of wind farm noise and replicated for the study’s participants in a lab. Sleep measurements were taken using electroencephalography (EEG), which measures brain activity while asleep.
“We became aware of public concerns and complaints around sleep disruption and annoyance around wind farm noise, as wind farms have expanded substantially in Australia and globally,”
New Australian research has found that noise from wind farms is no more disruptive to sleep than traffic sounds.
A study by sleep researchers at Flinders University revealed that very low-frequency wind farm noise is not audible to the human ear while awake or asleep.
In a project that took five years, more than 460 sleep study nights involving 68 participants were looked at.
They were recruited from four groups, including those living near a wind farm, those living near a busy suburban road and people living in quiet rural areas.
Each was played 20-second windfarm and road traffic noise samples repeatedly using three different sound pressure levels to compare their responses.
On a separate night, the study tested whether longer three-minute noise samples, including low-frequency windfarm sounds, resulted in sleep disturbance.
The researchers found that short exposure to windfarm and road traffic noise triggered a slight increase in people waking that could fragment their sleep patterns.
But it also showed that wind farm noise was no more disruptive than road traffic.
The study’s chief investigator, Prof Peter Catcheside, said the findings showed both wind farm noise and road traffic noise disrupted sleep, depending mainly on how loud they were.