Some Aspects of Analysis of Dolphins’ Acoustical Signals

Dolphins produce various types of sounds in a wide range of frequencies. Characteristics of some sounds till now have not been correctly registered, that influenced on interpretation of their functions. Studying of the characteristics and functions of dolphins’ acoustical signals is the purpose of the present work. In this work the acoustical signals of two dolphins (Tursiops truncatus) were registered by two-channel system in the frequencies band up to 200 kHz at quasi-stationary position of the dolphins. The dolphins along with whistles are producing the packs of coherent and non-coherent broadband pulses. The waveform and spectrum of coherent pulses was invariable within a pack, but considerably varies from a pack to a pack. The waveform of each non-coherent pulse vary from a pulse to a pulse in each pack, therefore their spectrum also vary from a pulse to a pulse and have many extremums in the band of 6 200 kHz. It is very likely that the non-coherent pulses play a part of phonemes of a dolphin spoken language and the probing signals of dolphin’s noncoherent sonar. The use possibility of the signals by dolphins for communication and orientation was considered, as the signals apparently are bimodal. Results of the work have significance for further studying of the dolphin’s sonar and spoken language.