Figure 5. Example of increasing received signal level of paired bursts for one whale when diving to the seafloor.

Relative received level of paired burst pulses from a single paired burst bout as mn09_201a, ‘Entropy' descends to the bottom with 0 dB referenced to the first detected paired burst pulse near the surface. Note the received level of the signals increased as the whale dived to the bottom, which was consistent for most paired bursts on this individual's tag record.