Introduction. A common regulatory acceptance criterion for wind turbine installation in Canada is that sound pressure level does not exceed 40 dBA outside a home when the wind speed at 10 metres elevation does not exceed 4 metres per second. A clue to the ineffectiveness of this criterion can be seen from over 2700 complaints filed in Ontario with regulators by residents living in homes where acoustic conditions were predicted in approved models to comply with the current criterion. Residents noted the intrusiveness of an imposed sound higher in amplitude and different in quality than the pre-existing background. Residents reported disrupted sleep, and adverse health consequences. Fundamental premises of Environmental Protection Acts (EPA) are that emissions of a contaminant such as noise should not cause an adverse effect including loss of enjoyment of normal use of property, or annoyance that lead to human health impacts. …
Discussion. The subject of amplitude modulation of wind turbine noise emissions (otherwise described as a cyclical noise rising and falling in magnitude) has been a principal focus of wind turbine noise international conferences in Glasgow (2015) and Denver (2013). Monitoring of the sound inside homes displays a different character than outside, showing pulses with peak to trough amplitudes exceeding 5 dB at frequencies that are within the audible range. A simple example shows that dBA weighting does not adequately reflect perception and annoyance. White noise at 40dBA has a very different perception than pink noise at 40 dBA.
William K.G. Palmer, TRI-LEA-EM, Paisley, Ontario
Canadian Acoustics – Acoustique canadienne Vol. 44 No. 3 (2016) – pp. 42-43
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