Figure 4
From: Vessel noise exposures of harbour seals from the Wadden Sea
Vessel pass with the highest maximum 2 kHz decidecade received level in the study. The top image shows a spectrogram of the power spectral density (PSD, i.e., power per 1 Hz band). The vessel noise in the recording is interrupted multiple times due to surfacing of the seal. The bottom image shows the corresponding 2 kHz decidecade band levels (blue line), computed as 30 s averages as described in the text, as well as broadband weighted sound pressure levels (SPL; orange line) from 500 Hz to 20 kHz following the frequency weighting for phocid seals in water (PCW) by Southall et al.37. The red dashed line illustrates the 97 dB detection threshold used to detect high noise events in the 2 kHz decidecade band.
