Attitude and Auralisation – The Virtualisation of Wind Farm Sound

Published by Etwas Luft. View the original article.

By Ketan Joshi,  Research and Communications Officer at Infigen Energy. These views are his own. 

If you’re looking for immediate confusion, the science of sound is a fantastic place to start. Some part of my brain seems to immediately shut down when confronted with the tricky task of trying to quantify the subjective experience of sound. It’s in this foggy field that most wind developers find themselves standing, when attempting to inform communities about the acoustic impact of wind turbines.

I was at Clean Energy Week last week, and I had a chance to experience a neat new tool developed by Arup, in conjunction with Hydro Tasmania, that seems to circumvent the need to communicate the complex (logarithms, what even are they) science of acoustic engineering.

On Thursday morning, I sat amongst six Genelec 8030A speakers, and one (beautiful) Genelec 7060B subwoofer, in front of a screen that displayed recorded video of a wind turbine (Genelec manufacture professional studio-grade speaker systems). The engineers had arrived much earlier the day before, and calibrated the device to account for the room. The speakers also cover most of the low-frequency range of wind farm sound as well – down to 40 hertz.

20130725_112312

The simulation began at two kilometres away, in high-wind conditions. The wind turbine was quite literally inaudible to me – listening closely for the characteristic whoosh of the blades, I really couldn’t detect anything. The interesting part is the background noise – when you’re listening extremely closely for wind turbine noise, there are times when the background noise can actually seem to mimic that whoosh, and you start questioning your own perception. But when the engineer flicked the background noise off, there was complete, utter silence.

Arup
The acousticians used a ‘Head-Related Transfer Function’ to adapt the experience for use with headphones instead of speakers – not as accurate, but still pretty close.

Moving closer to the wind farm, you can slowly start teasing apart the signal from the noise. The sound of the turbine is just audible at around one kilometre, but it’s very much mixed in against the background noise. Right up against the machine at 100 metres, the sound of the rotor is clearly audible, and you can actually hear some of the cooling gear in the nacelle. The sound at that distance isn’t offensive, but it’s certainly perceptible (100 metres also happens to be distance at which Greens MLC Mark Parnell camped out under a wind turbine).

Screen Shot 2013-07-30 at 4.49.34 PM

Because the experience is a mixture of real and simulated sound, the engineers can present a variety of wind conditions and locations – we were inside a bedroom with the window open, with the window closed, and at varying wind speeds. From my time on site at wind farms, I can testify that the representation is astonishingly accurate. The engineer behind the device informs me they hope to have the science behind the tool reviewed by another acoustics firm, some time soon.

20130725_112334

It’s an established truth that experiences are more memorable than numbers. When was the last time you decided that a light was bright by measuring its luminosity? You didn’t – you looked at it through your own trusted (and well-tested) machinery of perception. I suspect it’s very much the same with the experience of sound. If we’re told of a decibel output, it’s not really that memorable. But if we can experience an accurate representation of wind farm noise ourselves, it sticks with us.

Visiting a wind farm is great, and you get to experience it first hand, but you’re limited to one wind speed, and one wind direction. This ‘Auralisation’ tool seems to be able to accurately represent a variety of conditions, and I think the engineers at Arup deserve some credit for the rigour they’ve put into the science behind it.

5 thoughts on “Attitude and Auralisation – The Virtualisation of Wind Farm Sound

  1. I sat in on a simulation at Clean Energy Week. This device replicates the sound of a wind farm with uncanny accuracy. Fingers crossed for a mobile wind farm ‘auralisation’ which can tour Australia’s wind regions.

  2. Just basic arithmetic makes the whole thing look even sillier. If Ms Waubra is worried about 10Hz, because sound travels at more than 300m/sec in air, the wavelength of a 10Hz signal is 30metres! Need very clever modulation and/or huge speaker cone to simulate source noise. Will a microphone work at such low frequency or do you use an electronic pressure gauge/barometer? Maybe they should diversify a little, building up denialism about danger of witches and ghosts.

  3. This is a masterful effort at deliberately confusing the facts. To paraphrase an old saying, “If your efforts to manipulate the scientific facts fail miserably, do your best to confuse the public with utter bullshit”.

    Even the smallest wind farm installation constitutes hundreds of thousands of cubic metres of air, plus the varying effects of atmosphere and landscape.

    How do you simulate that in a studio?

    Y2R is getting desperate.

  4. Like I have said before the sound may not affect all but may affect some just like sea sickness. Someone that does not suffer sea sickness does not comprehend how debilitating it can be. Providing a buffer distance can be the answer. 2km from a home was recommended by the Retexxo Grupp in Germany. I personal favour 20x the height to blade tips or 2km whichever is greater.

  5. What sound according to you guys wind turbines are so quiet like a fridge at 300m you cant even hear them.Are you saying they do make noise now.More industry funded rubbish.Like the smoking industry told us its good for you.As long as you keep rolling out things like this funded by the same fossil fuel owned wind companies that benefit from it people will always smell a rat.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s