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Spatial and temporal trends in fin whale vocalizations recorded in the NE Pacific Ocean between 2003-2013

Fig 6

Illustration showing the relationship between peaks in two-dimensional frequency-IPI histograms and the singlet and doublet songs.

Following Fig 5, frequency is plotted along the x-axis and inter-pulse interval along the y-axis. A-note singlet songs, with higher IPI and lower frequency appear in the upper left. A notes from doublet songs have a similar frequency but appear in the lower left. B notes from doublet songs appear in the lower right. The peak that is sometimes observed in the upper right is an artifact and it occurs when lower amplitude A notes that are part of A/B doublet songs are not detected.

Fig 6