Interesting properties of toothed whale buzz clicks

Toothed whales are known to click to find prey. The characteristics and repetition rates of the echolocation clicks vary from one species to another, but clicks are fairly regular during the phase in which the animals are searching for prey. Once they have found prey the repetition rate of the clicks increases; these sequences are called buzzes. Some previous work was done to classify Blainville’s beaked whale buzz clicks. While we did not succeed to classify these clicks individually because of the variation of their characteristics, we found buzz clicks have slowly varying properties from one click to the next. This similarity permits their association as a sequence using multi-hypothesis tracking algorithms. Thus buzz classification follows the automatic tracking of clicks. We also found that buzz clicks from other toothed whales species often have similar properties. In some cases a variant of this property has been found, whereby sub-sequences of clicks also exhibit slowly varying characteristics.