Noise from the proposed Te Uku wind farm will be no more than minor for neighbours, according to a Wel Networks-appointed acoustics expert.
Fears of noise from the “woosh” of wind turbines have been a significant concern for opposing submitters, often accentuated by information available on the internet.
But acoustic consultant Nevil Hegley told a Resource Management Act hearing in Ngaruawahia yesterday there was no factual evidence to suggest there will be any significant adverse effects from wind farm noise, and outlined technological improvements.
Mr Hegley said as blade aerofoils have become more efficient, more of the wind is converted into rotational torque and less into acoustic noise.
“It is important to appreciate that the older style turbines … had two blades, not three,” he said. “Older two-bladed turbines are noisier than the modern three-bladed equivalents.”
Aerodynamic noise had also been further reduced by changing the thickness of the blades’ trailing edges and by making machines “upwind” rather than “downwind” so that the wind hits the rotor blades first, then the tower.
Mr Hegley has assessed 16 proposed or existing wind farms in New Zealand.
In addressing the potential for low frequency (below 200Hz) noise, he said he found no factual basis for suggestions low-frequency noise touted in some quarters as having been used as an instrument of torture by the Nazis during World War II because it induced headaches and anxiety attacks could disturb rest and sleep and cause an increase in depression.
He said there were more than 50,000 wind turbines in operation globally some for more than 20 years but no evidence to link low frequency noise from wind turbines with impacts on human health.
He quoted an English researcher who suggested there might be an alternative reason for people experiencing adverse symptoms. “We have to keep in mind that people who have failed, for whatever reason, in strong objections to a development, build up in themselves a level of unfulfilled expectations and consequent stress which peaks after the failure and can overload their coping capabilities.”
By Bruce Holloway
22 November 2007
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