Fig. 2.

Peak detection in the HFO range. This figure illustrates the procedure we followed for HFO peak detection applied to a case with pronounced 50 Hz harmonics. Firstly, spectral values within 3 Hz around harmonics were removed and interpolated (A). Secondly, the interpolated time series was low-pass filtered and a linear slope spanning the 100–400 Hz range was determined based on the average power within the 100–110 Hz and 390–400 Hz intervals shown in orange (B). The linear slope was then subtracted from the smoothed curve and the maximum value of the resulting curve was detected (C).