Figure 1
From: Marine mammal acoustic detections in the Greenland and Barents Sea, 2013 – 2014 seasons
Spectrogram of a sequence of 20 Hz fin whale signals (time scale 2:00 min, linear frequency scale 0–150 Hz). The spectrogram shows the typical 20 Hz single downsweep signals, repeated every ±14 s. A higher frequency energy component around 127–131 Hz coincides with the temporal pattern of the 20 Hz signals, starting less than 0.5 s before the start of the latter and overlapping with it temporally.
