Bayesian detection and tracking of odontocetes in 3-D from their echolocation clicks

Abstract

Localization and tracking of marine animals can reveal key insights into their behaviors underwater that would otherwise remain unexplored. A promising nonintrusive approach to obtaining location information of marine animals is to process their bioacoustic signals, which are passively recorded using multiple hydrophones. In this paper, a data processing chain that automatically detects and tracks multiple odontocetes (toothed whales) in three dimensions (3-D) from their echolocation clicks recorded with volumetric hydrophone arrays is proposed. First, the time-difference-of-arrival (TDOA) measurements are extracted with a generalized cross-correlation that whitens the received acoustic signals based on the 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 MTT method using 3-D can outperform an existing approach that relies on manual annotation.

Where’s Whaledo: A software toolkit for array localization of animal vocalizations

“…To improve Where's Whaledo, a more advanced detector could be used to incorporate low SNR clicks without generating false detections. Jang et al [16] implemented a Generalized Cross-correlation detector on the same dataset, which was effective in removing most false detections caused by repeated instrument sounds.…”

“…Additionally, Jang et al [16] used a multi-target tracking (MTT) algorithm to reconstruct Ziphius cavirostris tracks using the two small aperture volumetric arrays.…”

“…Passive acoustic localization of cetacean vocalizations using arrays of hydrophones has been used to reconstruct tracks of a number of cetacean species, like Cuvier's beaked whales (Ziphius cavirostris), common dolphins (Delphinus delphis), and sperm whales (Physeter macrocephalus)( [13][14][15][16][20][21][22][23][24][25]. Different approaches to localization have been implemented for different configurations of hydrophones, and to observe different species or behaviors of interest.…”

“…Automated tracking methods are emerging which use advanced multi-target tracking algorithms to identify source associations, remove false detections, and estimate likely tracks using two volumetric arrays for encounters with simultaneous detections on both arrays. [16]. Due to the directional nature of many species' echolocation clicks [13,37], simultaneous detections become increasingly uncommon as the distance between the instruments increases.…”

AOA positioning algorithm based on three-dimensional space

“…The cross directionpositioning method is one of the most widely used passive positioning methods [1][2][3][4][5][6] . It uses high direction finding equipment to measure the direction of the target at two or more observation points.…”