Submission of Emeritus Professor Colin H Hansen
to the Australian Senate Select Committee on Wind Turbines.
Thank you for the invitation to provide a submission to this enquiry. My submission is relevant to items (c), (d), (e) and (f) in the terms of reference, as these relate to my areas of expertise which include acoustics, vibration, and noise measurement and assessment. As you will be aware, the recent NHMRC study concluded that “there is currently no consistent evidence that wind farms cause adverse health effects in humans”. However, there are also no studies that show that wind farm noise does NOT cause adverse health effects in humans, but this seems to have been forgotten.
The NHMRC information paper on which the NHMRC conclusion was based is flawed for a number of reasons which were pointed out to (but ignored by) the NHMRC. Some of these reasons are listed below. More details are provided in my review of the NHMRC draft information paper (included as an appendix to this document).
- The criteria used in the information paper to decide which research papers were worthy of being included in the study are obviously flawed as papers by many well-known scientists published in internationally recognised journals were rejected, yet one report by a resident near the Waterloo wind farm who has had no research training was included. Even the included papers were labelled as “poor in quality”, which then leads to the inevitable conclusion that there is “no consistent evidence that wind farms cause health effects in humans”.
- The assumption that wind farm noise is like any other noise of the same A-weighted decibel level is flawed. The authors of the information paper used this to justify why in the absence of high-quality studies on wind farm noise, they could use “studies on the health effects of similar emissions from other sources to inform its consideration of the direct evidence and in forming its overall conclusions”. Our measurements of wind farm noise in and around residences in the vicinity of wind farms indicate that wind farm noise is very different to other environmental noise such as traffic noise at the same A-weighted noise level (which I assume is the measure used by the information paper authors to define a “similar emission”). The difference lies in the low-frequency dominance of the noise produced in residences by wind farms, which is not quantified very well by the A-weighting metric. The other problem is that wind farm noise is highly variable and in many cases it varies at a regular rate so it sounds like “pulsing” or “thumping”, much like the bass sound from a party people may be having next door. Unfortunately this does not stop at midnight but may continue all through the night for several nights in a row before there is any respite. It is well known that this type of noise is annoying. It is also well known that some people annoyed by noise have difficulty sleeping and that sleep deprivation can lead to health effects, yet the authors of the information paper could find no evidence to support these well known facts.
- The assumption that the A-weighting measure can be directly related to the effect that noise has on people. This assumption showed no appreciation of the fact that the A-weighted noise level typically reported is a level that has been averaged over a period of time, usually between 10 and 15 minutes. Wind farm noise varies considerably over short periods of time and the peak levels can be much greater than levels averaged over 10 to 15 minutes.
- The assumption that A-weighted levels recommended by the World Health Organisation to avoid sleep disturbance, which were derived from traffic noise studies in urban areas would also apply to wind farm noise in rural areas. This ignores the fact that background noise levels in rural areas (especially in Australia) are well below background noise levels in urban areas and wind farm noise has entirely different characteristics to traffic noise, which makes it more intrusive and annoying.