Analysis of acoustic signals and cetacean biosonar intrinsic mechanism.

As sound propagates in water better than any other form of energy, cetaceans have developed accordingly a diverse intra- and interspecific acoustic repertoire. This diversity makes the study of cetacean vocalizations a captivating topic for signal processing techniques.

As an example, their analysis can face us with the challenge of detecting and isolating these signals in such a way that its characteristics remain preserved. This characteristic information might be found in the time and frequency domains of a single signal or only become apparent in longer sequences. The examination of these parametres can tell us more about the cetacean biosonar mechanism and lead to other applications, like the ability to uniquely identify an individual within a large group.

One of the complications when searching for this kind of information is the influence of noise on the signal. Furthermore, the characteristic information may also be affected by the current activities of the animal, its swimming depth or heading. Additional distortions of the signal can come from reverberations directly from the animal anatomy or multipath propagation.

In order to overcome these difficulties, the LAB is studying the fundamental properties of the acoustic cetacean signals and approximating the sonar signal by a parametric wave form model: the elementary Gabor time function as well as by Wavelet Analysis Techniques to improve our understanding of the usage and purpose of the signals themselves and subsequently to apply this knowledge in other applications.