Detection of sperm whale clicks based on the Teager-Kaiser energy operator

The development of an algorithm for automatic detection of sperm whale clicks in large recordings is described. It is based on the Teager-Kaiser (TK) energy operator and it is able to detect efficiently creaks as well as regular clicks. A matching filter is first used as a pre-processor in order to overcome the difficulties caused by the multi-pulse structure of regular clicks, Next, the TK energy operator is applied to the output of the matching filter. A first selection of clicks is performed based on statistical measurements on the TK output, while the final selection is carried out by a forward-backward search algorithm. The proposed system has been tested on a total duration of 25 min of data containing regular clicks as well as creak clicks, where the location of clicks has been marked by hand. An average rate of 94.05% of correct detections was achieved by comparison with the hand-labeled data created from the tested files. Comparing to a standard method used for the same task, the proposed algorithm is more effective in detection rate by 30% and much more accurate and robust. (c) 2006 Elsevier Ltd. All rights reserved.