Wind Farm Noise Management Based on Determinants of Annoyance

Comment: This paper makes some very good points and I feel it provides a cohesive, if not complete, viewpoint on annoyance in wind farm noise. In particular the overarching push to move away from sound-level-focussed mitigation to an emphasis on perception is crucial. However, I feel the singular focus on annoyance misses two key aspects in how people perceive and respond to sound. The first is the second primary dimension of soundscape perception eventfulness (Axelsson, 2010). By only focussing on the annoying/pleasant dimension, we restrict what is a complex multi-dimensional perception into only a single dimension. Since, in Axelsson's model of soundscape, eventfulness (or arousal) is orthogonal to pleasant/annoying, it opens up the perceptual space and provides a new metric to help explain the variance discussed in this paper. In addition, recent evidence suggests that the acoustic characteristics (i.e. sound level) have more of a direct impact on the perceived eventfulness of a soundscape than on the annoyance which is more dependent on contextual factors (including the representation of the source, as noted by the author) .

This is important as the eventfulness dimension can greatly influence the perceived character of a sound; for instance, consider an existing calm soundscape. Upon the introduction of a wind turbine at a relatively low sound level which is not expected to be highly annoying, the surveyed annoyance is higher than expected. How would this be explained? Perhaps the turbine was not loud enough to directly impact on annoyance, however it increased the eventfulness, turning this calm soundscape into an 'exciting' or arousing soundscape which now clashes with the expectations for the space. It is then this mismatch of people's expectations for the space which causes them to dislike the new soundscape, not necessarily anything about the direct impact of the sound level.

This also highlights the second aspect I feel is missed by a singular focus on annoyance the other side of annoyance, pleasantness. While wind farm noise is clearly primarily a noise source and in itself would not improve the pleasantness of a soundscape, how it integrates with (or fails to integrate with) the existing soundscape can have more complex effects than may be measured in terms of annoyance. The limit here is language and measurement -- if we are not measuring the impact on the overall perception of how pleasant the soundscape is, then we may miss aspects of how the introduction of turbines is affecting the population. Increased annoyance is not precisely the same as decreased pleasantness or decreased comfort and may only occur after a certain threshold is reached. When the questions and perception data we are collecting only ask about annoyance we may miss more subtle effects which could be captured by broadening the language beyond asking about the negative. The focus in mitigation can (and in the case of wind farms, should) remain on decreasing negative impacts, but how those impacts are measured and identified should not be limited to only annoyance.

The author makes a brief mention of these other dimensions of soundscape perception, but notes that only annoyance is considered in environmental assessments. I'd argue that, in addition to the great suggestions made by the author particularly about including considerations of worry and the ability to participate in the siting process, these other dimensions should also be considered in order to provide a more well-rounded view on the perception. Overall though, a wonderful discussion of a better approach to wind farm noise and I'm happy to have read it.