Frequency based Algorithm for Robust Contour Extraction of Blue Whale B and D calls

The sea is home to a myriad of marine animal species, many of which use sound as a primary means of communication, navigation and foraging. Of particular interest are the Blue whales (Balaenoptera musculus) of the cetacean family. Massive commercial whaling prior to 1960 brought the species close to extinction and its population still remains very low. Passive acoustic monitoring of baleen whales has recently been used to provide long-term information about their presence and behavior, and provides an attractive complement to traditional visual based monitoring. In this work we present a frequency domain based algorithm developed for extracting the frequency contours of the dominant harmonic in tonal calls of blue whales (B and D calls). The algorithm uses a two pass approach to contour extraction. In the first pass, partial candidate contours are formed, followed by a second pass which uses the partial information to construct complete contours. When evaluated on a one hour labeled recording, the algorithm had 90% recall and 76% precision.