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October 2008 Calendar

CS Masters' Thesis Defense

Title: Automatic Detection of Free-Ranging Blue Whales' D and B Calls in the Presence of Multiple Cetacean Species
Speaker: Shyam Madhusudhana
Date: Tuesday, October 7, 2008
Time: 11:00 a.m.
Location: GMCS 405
Thesis advisor: Dr Marie Roch

Abstract:
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 solution for the automatic detection of two types of blue whale vocalizations. A frequency domain based algorithm was 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. An expert system based classifier was developed which takes the extracted frequency contours as inputs and classifies them as either B or D calls, or rejects them depending upon their characteristics. When evaluated on a one hour labeled recording, the contour extraction algorithm had 96.8% recall and 98.5% precision. The classifiers had an average recall of 91% and an average precision of 96.7% on the same set.

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