Thursday 15 October 2009

THE INVERSE SQUARE RULE

Windfarms are noisy.

They're not, of course, but this is what the nimbies keep telling us. They're noisy, so there.

But what happens when someone actually visits a windfarm, or stays near one, and discovers that they're remarkably, surprisingly quiet?

Each time that happens - each time somebody returns to the Shire with the news that it's possible to stand directly beneath the blades of a working wind turbine and still be surprised by how quiet they are - the nimbies are caught out. Telling porkies again. Windfarms aren't noisy at all.

So the nimbies have been employing a cunning new weapon. When it is pointed out that so-and-so actually stood directly beneath the blades of a turbine on a windy day and says they're not noisy, the nimby response will be:

'Of course. Sound travels outwards. Wind turbines get noisier the further you are from them!'

This claim has the appearance of science to support it. Soundwaves radiate outwards from a source. If you're right up against the source, the soundwaves will be heading outwards into the atmosphere above your head. You won't hear them, but somebody standing further away will.

Unfortunately for the nimbies, this argument is sheer cobblers.

Sound follows the inverse square rule. The volume of a sound diminishes rapidly as you move away from it.

This is why modern turbines can barely be heard 200 metres away. Up close, they're very quiet. Even that low level sound quickly disappears as you move away from the masts.

So, no - wind turbines do not get noisier the further you move away from them.

Science nails another nimby myth.

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