The South Australian EPA has released a report titled "Infrasound levels near windfarms and in other environments". This report presents the findings of a study into the level of infrasound within typical environments in South Australia, with a particular focus on comparing wind farm environments to urban and rural environments away from wind farms.

Importantly, the report is based on actual measurement of infrasound around existing wind farms and other urban and regional areas.

The key findings include:

• Infrasound levels measured at houses adjacent to wind farms are no higher than those measured at houses located a considerable distance from wind farms
• Infrasound levels in the rural environment appear to be controlled by localised wind conditions. During low wind periods, levels as low as 40dB(G) were measured at locations both near to and away from wind turbines. At higher wind speeds, infrasound levels of 50 to 70dB(G) were common at both wind farm and non-wind farm sites.
• Organised shutdowns of the wind farms adjacent to measurement locations indicate that there did not appear to be any noticeable contribution from the wind farm to the G-weighted infrasound level measured at either measurement location.
• This suggests that wind turbines are not a significant source of infrasound at houses located approximately 1.5 kilometres away from wind farm sites.

From an overall perspective, measured G-weighted infrasound levels at rural locations both near to and away from wind farms were no higher than infrasound levels measured at the urban locations. Furthermore, both outdoor and indoor infrasound levels were typically below the perception threshold by a significant margin. The most apparent difference between the urban and rural locations was that human activity and traffic appeared to be the primary source of infrasound in urban locations, while localised wind conditions are the primary source of infrasound in rural locations.

An additional analysis of the frequency content of the measured infrasound levels was conducted for each location. At both of the wind farm sites, peaks in the frequency spectrum corresponding to the turbine blade pass frequency and related harmonics (0.8Hz, 1.6Hz and 2.5Hz) were identified that may be attributable to the wind turbines. However, these peaks were only detectable during periods of low wind speed and therefore ambient infrasound at the residences. The peaks in the spectrum were found to be no higher than infrasound levels measured at these frequencies at both rural and urban locations away from wind farms, and also significantly (at least 50dB) lower than the threshold of perception for these very low frequencies.