  Localizing and tracking of marine mammals can reveal key insights into
behaviors underwater that otherwise would remain unexplored. A promising
nonintrusive approach to obtaining location information of marine mammals is
based on recordings of bio-acoustic signals by volumetric hydrophone arrays.
Time-difference-of-arrival (TDOA) measurements of echolocation clicks emitted
by odontocetes can be extracted and used for detection, localization, and
tracking in 3-D. We propose a data processing chain that automatically detects
and tracks multiple odontocetes in 3-D from their echolocation clicks. First,
TDOA measurements are extracted with a generalized cross-correlation that
whitens received acoustic signals based on instrument noise statistics.
Subsequently, odontocetes are tracked in the TDOA domain using a graph-based
multi-target tracking (MTT) method to reject false TDOA measurements and close
gaps of missed detections. The resulting TDOA estimates are then used by
another graph-based MTT stage that estimates odontocete tracks in 3-D. The
tracking capability of the proposed data processing chain is demonstrated on
real acoustic data provided by two volumetric hydrophone arrays that recorded
echolocation clicks from Cuvier's beaked whales (Ziphius cavirostris).
Simulation results show that the presented 3-D MTT method can outperform an
existing approach that relies on hand annotation.
