Living near a wind turbine could harm emotional wellbeing after scientists discovered that low frequency sounds generated by rotor blades trigger a part of the brain which senses danger.
Wind farm critics have long complained of the detrimental impact of turbines on their mental health, sleep patterns and physical wellbeing.
But now a study suggests that the brain can register low frequency sounds even below the level of normal human hearing.
Brain scans show that even infrasound as low as 8hz – a whole octave below the traditional cut off point for human hearing – is still being picked up by the primary auditory cortex, the part of the brain which translates sounds into meaning.
And a separate part of the brain, linked to emotions, also lit up when the seemingly ‘inaudible’ noises were played to volunteers in a lab.
Dr Christian Koch of the Max Planck Institute for Human Development in Berlin said: “The observations showed a reaction in certain parts of the brain which play a role in emotions.
“This means that a human being has a rather diffuse perception, saying that something is there and that this might involve danger.
“All persons concerned explicitly stated that they had heard something.”
People living in the vicinity of wind farms have long reported experiencing sleep disturbances, a decline in performance, and other negative effects, apparently from the “infrasound” generated by the turbines
But the wind energy sector has always maintained that the sounds created by rotor blades are too low a frequency to be picked up by humans.
To test whether sounds could be heard the team generated an infrasonic source which is able to create sounds that are completely free from harmonics.
Volunteers were asked about their hearing experience, and these statements were then compared by to their brain scans.
The results revealed that humans hear lower sounds from around 8 hertz on – a whole octave lower than had previously been assumed.
Infrasound is not only produced by wind turbines, but also sometimes when a truck thunders past a house, or when a home owner installs a power generator in his basement.
Last year a University of Munich study found that exposure to low frequency sound could affect human hearing.
But then wind farm owners pointed out that the level of sound used in the study was significantly higher than the levels now emitted from turbines. A separate report by the Energy and Policy Institute in Washington, also concluded that sickness caused by wind turbines was not a real illness. The authors concluded that symptoms such as nausea, dizziness and migraines were simply imagined by those living nearby.
Dr Koch added: Neither scaremongering nor refuting everything is of any help in this situation. Instead, we must try to find out more about how sounds in the limit range of hearing are perceived, Further research is urgently needed.”
RenewableUK’s Director of Onshore Renewables, Gemma Grimes: “The wind industry takes all health and safety issues very seriously. This piece of work was, by the author’s own admission, just him thinking aloud and raising a number of possible issues relating to all types of infrastructure that could be researched further – he undertook no research at wind farms.
“The author himself stated that it would be scaremongering to make any a connection between wind farms and public health issues. There is an existing body of peer-reviewed scientific research, which clearly shows that living near a wind farm has no adverse effect on anyone’s health, and to suggest otherwise is inaccurate and irresponsible”.
The project, which is part of the European Metrology Research Programme (EMRP), was coordinated by the German National Metrology Institute (PTB).
CORRECTION: The University of Munich research mentioned in this article did not examine “noise levels similar to living near wind farms”, as reported in an earlier version, nor did it find that these “could lead to severe hearing damage or even deafness”. Rather, it noted effects that could indicate possible damage to the inner ear following exposure to low frequency sound – albeit at levels higher than permissible for wind turbines. The article has been amended accordingly.
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