Considerations regarding an acoustic criterion for wind turbine acceptability

Abstract

A common criterion for approval of wind turbine installation in Canada is that sound pressure level does not exceed 40 dBA outside the home of a rural receptor when the wind speed at 10 metres elevation does not exceed 4 metres per second. This paper looks at other considerations that might be considered based on the experience following installation of wind turbines using the common criterion. Thousands of complaints filed with regulators from residents living in homes approved under the current acceptability criterion provide clues. Residents note the intrusiveness of an imposed sound much higher in amplitude and different in quality than the natural background. Residents report disrupted sleep, and adverse health consequences that follow. 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. The fundamental premise of Environmental Protection Acts are that emissions of a contaminant such as noise do not cause an adverse effect including loss of enjoyment of normal use of property, or annoyance that lead to human health impacts. Experience has shown the current criterion is not allowing this fundamental premise to be achieved.