Low Frequency, Infrasound and Amplitude Modulation Noise from Wind Farms – Some Recent Findings

INTRODUCTION Recently, amplitude modulation, low frequency and infrasound noise from wind farms has been the subject of complaints, many different media reports and a Senate Inquiry in Australia. The Ministry of Environment of Ontario province in Canada, amongst many other regulators, has been considering a new policy on low-frequency infrasound noise from wind farms and commissioned a literature review into it in 2011. That report collated and considered many papers dealing with the audibility of low-frequency sound and noise from wind farms. Some of the papers presented at Inter-Noise 2011 in Osaka included measurements or predictions of sound levels and frequency spectra from wind turbines, including the low-frequency range and amplitude-modulation. These papers help provide some further information to acousticians dealing with wind farm noise. Broner [1] suggested an environmental noise quality criterion for low-frequency sound, based on the C-weighted sound level. Comment is provided using comparisons of lowfrequency and infrasound hearing thresholds with measured wind turbine sound frequency spectra, and amplitudemodulation sound levels from wind turbines.