SPP over rotational speed for all considered 10-min time windows at the four ground motion measurement sites shown in Figure 2. The detection threshold for AM is set to 2 dB for the SPP method, indicated by the red dashed line. Lower SPP values occur for all rotational speeds and, therefore, only above this threshold detections are reasonable. Only at the site in 70 m distance to WT 2 SPP values of more than 2 dB are observed for multiple time windows.