Automated tracking of multiple acoustic sources with towed hydrophone arrays

Abstract

Line transect surveys often incorporate a towed hydrophone array to detect and localize marine mammals. The animals are typically tracked based on the estimated time difference of arrivals (TDOAs) of their calls between pairs of hydrophones. The estimated TDOAs or bearings are then tracked through time to obtain animal or group positions, a process often performed manually. This process can be especially challenging in the presence of multiple animal groups that are vocalizing simultaneously, but at the same time do not emit signals consistently through time. In addition, the process is hindered by missed detections and false alarms (false TDOAs). Here, an automated approach to TDOA tracking is outlined, based on a multi-target Bayesian framework, that incorporates target appearance, disappearance, missed detections and false alarms. The method is demonstrated on examples of line transect surveys from Western Canada [Norris et al., J. Acoust. Soc. Am.146, 2805 (2019)] and from Hawaii, USA. [In memory of Thomas F. Norris.]