Physicists have learned to distinguish between the dialects of dolphins
Common issues
Image: F. Specht, Royal Natural History, 1893
A group of physicists and marine biologists from Norway and Germany have created an algorithm that can most objectively analyze the sounds of an ordinary pilot (Globicephala melas) and even to distinguish between dialects between different groups.It is built on the cepstrum analysis of whale sounds and can help in studying social relationships within and between groups of animals, direct observation of which complicated. A study published in the journal Physical Review E(Preprint), briefly about it, reports Physics.
The authors studied six different groups of pilot whales near the coast of Norway. Instead of identifying the sounds each animal group separately, scientists have analyzed all the sounds produced by each group. For each group was done a few hundred records. On the basis of the amplitude-frequency characteristics of scientists built the so-called cepstra, spectra spectra, after which they were processed statistically.
The distribution of cepstral coefficients between the different groups of pilot whales
Image: Heike Vester et al./ arXiv.org, 2015
Physics were evaluated by a special quantitative characteristics of cepstral parameters responsible for the changing characteristics of the sound over time. It turned out that the variance within one group is much smaller than between two different groups. The authors note that such a machine way of handling “songs” is much more objective than the separation of sounds based on human perception. In the latter case there is the risk of missing any particular sounds that are important for the Blackfish.
Spectrogram of clicks and “hum” made by the pilot
Image: Heike Vester et al./ arXiv.org, 2015
Cetaceans produce a variety of sounds — whistles, clicks and buzzing at different frequencies. Observations of sperm whales and killer whales biologists have any theory of the existence of their peculiar dialects, which differ from group to group. As a rule, in nature, these vocal differences are associated with large distances between individual populations, however, in the case of, for example, sperm whales, they can even occur between groups inhabiting the same territory.
Vladimir Korolev
