This was the sixth down from the top when I googled "windmill noise kilometers". https://news.flinders.edu.au/blog/2019/06/19/wind-farm-noise-recorded-almost-9

This was the sixth down from the top when I googled "windmill noise kilometers". https://news.flinders.edu.au/blog/2019/06/19/wind-farm-noise-recorded-almost-9km-away/ https://news.flinders.edu.au/blog/2019/06/19/wind-farm-noise... It is notable that the two papers mentioned used different criteria. The one claiming long-distance disturbance used "audible indoor", while the one casting doubt used "unlikely to cause problems".