Wind turbine infrasound: What’s all the noise about? by Richard Mackie

On Wednesday the Senate inquiry into excessive noise from wind farms released their report. The inquiry was supposed to focus on audible noise but debate strayed into concerns that wind turbines can cause health problems by producing infrasound (sound of a frequency so low that it is normally inaudible) and low frequency noise.

Wind farm opposition groups such as the Waubra Foundation are prone to making extreme statements about wind turbines such as this from their senate inquiry submission "...characteristic symptom patterns have been reported at distances up 10km away from the nearest wind turbine." Infrasound is blamed and understandably people get concerned.

So where does this idea come from? The Senate inquiry gives us the answers. Submissions represent a global who's who in the debate on wind farms and health. Often information provided to support the wind farms-cause-health-problems idea actually demonstrates the opposite.

Take for example Figure 1, presented by Steven Cooper of the Acoustics Group in senate inquiry submission no. 142. The Acoustics Group is used by opponents to wind farms in support of their submissions opposing proposed wind farms including: the Flyers Creek wind farm project in New South Wales and the Stony Gap and Hallet 3 projects in South Australia.

In presentations promoted by Senators Xenephon and Madigan, Cooper has quickly flashed through this graph and others in order to bolster the case that wind turbines could be causing health problems. I went to his presentation in Bacchus Marsh on 13th of June this year and witnessed this. Rather strangely, Cooper refused to provide a copy of his presentation even though he had just publicly presented it, despite requests from many members of the audience. What's the secret? Particularly when Cooper goes to great lengths to say that “If there is potential for an industry to jeopardise the welfare, health or safety of the public, or affect the well being of the community I am duty bound to identify those issues under the Code of Ethics of the Australian Acoustical Society.” (inquiry submission no. 142).

Examination of Figure 1 shows that peak infrasound (sound below 20Hz than cannot usually be heard) recorded by Cooper inside a house near to a wind farm was about 50dB at very low sound frequencies of around 2 Hz, fading quickly to almost nothing at 8 Hz.