Echolocation Clicks from Three Species of Odontocetes

A species classifier is presented which decides whether or not short groups of clicks are produced by one or more individuals from the following species: Blainville’s beaked whales, short-finned pilot whales, and Risso’s dolphins. The system locates individual clicks using the Teager energy operator and then constructs feature vectors for these clicks using cepstral analysis. Two different types of detectors confirm or reject the presence of each species. Gaussian mixture models (GMMs) are used to model time series independent characteristics of the species feature vector distributions. Support vector machines (SVMs) are used to model the boundaries between each species’ feature distribution and that of other species. Detection error tradeoff curves for all three species are shown with the following equal error rates: Blainville’s beaked whales (GMM 3.32%/SVM 5.54%), pilot whales (GMM 16.18%/SVM 15.00%), and Risso’s dolphins (GMM 0.03%/SVM 0.70%). SOMMAIRE Ce travail concerne la création d’un système pour identifier trois espèces d’odontocètes par les clics d’écholocation: la baleine à bec de Blainville, la baleine pilote, et le dauphin de Risso. Les clics sont identifiés par l’opérateur d’énergie Teager-Kaiser, et les vecteurs cepstraux sont construits. Dans un travail de détection, on compare les résultats obtenus avec deux modèles différents : le modèle de mélange gaussiens (MMG) et la machine à vecteurs de support (MVS). Les résultats de la détection sont exprimés par les courbes de DET, « Detection Error Tradeoff». Le point sur les courbes de DET où les probabilités de fausses alarmes et manques de détection sont égales est comme suit : la baleine à bec de Blainville (MMG 3,32%/MVS 5,54%), la baleine pilote (MMG 16,18%/MVS 15,00%) et le dauphin de Risso (MMG 0,03%/MVS 0,70%). 1. i n t r o d u c t i o n The use of acoustic information for study of marine mammals is a promising method that is complimentary to visual observations. One use of acoustics is to determine the presence of species of interest, the so called detection problem. In this work, we describe a detection system implemented for the 3rd International Workshop on the Detection and Classification of Marine Mammals Using Passive Acoustics, a conference which brought together multiple groups to work on a common data set containing calls from Blainville’s beaked whales (Mesoplodon densirostris), short-finned pilot whales (Globicephala macrorhynchus) and Risso’s dolphins (Grampus griseus). Low error-rate detections were achieved for all three species using both Gaussian mixture models (GMMs) and support vector machine algorithms.