|Title||Automated acoustic localization and call association for vocalizing humpback whales on the Navy's Pacific Missile Range Facility|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Helble T.A, Ierley G.R, D'Spain G.L, Martin S.W|
|Journal||Journal of the Acoustical Society of America|
|Type of Article||Article|
|Keywords||algorithm; arrival; function minimization; hydrophone array; locations; marine mammals; ocean; probability; sensors; tracking|
Time difference of arrival (TDOA) methods for acoustically localizing multiple marine mammals have been applied to recorded data from the Navy's Pacific Missile Range Facility in order to localize and track humpback whales. Modifications to established methods were necessary in order to simultaneously track multiple animals on the range faster than real-time and in a fully automated way, while minimizing the number of incorrect localizations. The resulting algorithms were run with no human intervention at computational speeds faster than the data recording speed on over forty days of acoustic recordings from the range, spanning multiple years. Spatial localizations based on correlating sequences of units originating from within the range produce estimates having a standard deviation typically 10 m or less (due primarily to TDOA measurement errors), and a bias of 20 m or less (due primarily to sound speed mismatch). An automated method for associating units to individual whales is presented, enabling automated humpback song analyses to be performed.
The techniques outlined in this paper prove to be effective for localizing humpback whale vocalizations on 14 hydrophones five times faster than real-time on the PMRF range with a predicted high level of spatial accuracy. The localization process is robust over a wide range of environmental and noise conditions, and has been shown to work on data collected in the months of December to May over multiple years. Although not discussed in detail, the GPL detection and templating procedure is general enough to be readily adapted to other types of marine mammal vocalizations, and so the same process for obtaining TDOAs between hydrophone pairs can be ported to other species.