Wind Turbine and Wind Farm Sound Levels: A Prototype Journey

Geoff Henderson

New Zealand Acoustics, 20(4), pp.15- 22 . (2007).

The wind energy industry is booming in New Zealand and presents a new set of challenges to the acoustics industry. The NZ Standard NZS 6808:1998 ‘Acoustics – The Assessment and Measurement of Noise from Wind Turbines’ provides guidelines on the way in which sound from wind turbines should be measured and assessed and the levels of sounds that are acceptable. As part of its resource consent conditions for a New Zealand designed and manufactured 500 kW wind turbine at Gebbies Pass near Christchurch in July 2003, Windflow Technology offered to do better than the guidelines and be no louder than 30 dBA at the boundary (including tonal penalty). This paper outlines the process of estimating the sound levels in the area, determining the sound source when the turbine was found to be over the limit, and the results from implementing the solution. The paper also raises other unique issues in measuring sound levels in different wind conditions and topography, and low frequency/infrasound concerns that are arising.