Study of the relationship between pilot whale (Globicephala melas) behaviour and the ambiguity function of its sounds

Abstract

Pilot whales produce clicks, whistles and pulsed calls, which form a key component of their social lives. The three types of sound driven by their behavioural states are not directly observable. The mathematical tools which compute properties of sound are natural candidates for analysing the possible relationship between pilot whale sound and behaviour. In this paper, the wideband ambiguity function is used to compute the range resolution, speed resolution, Doppler tolerance, sidelobe-to-mainlobe suppression ratio of the range ambiguity function and sidelobe-to-mainlobe suppression ratio of the speed ambiguity function for pilot whale sound, which can be used to evaluate the abilities of pilot whale sound in detecting targets and resisting the influence of relative speed. Statistical results show that clicks have the best range resolution and its range ambiguity functions have the lowest sidelobe-to-mainlobe suppression ratio. Pulsed calls and part of the whistles have the best speed resolution and its speed ambiguity functions have the lowest sidelobe-to-mainlobe suppression ratio. The other part of whistles has a large Doppler tolerance. Analyzing the five parameters of different types ofsound and the corresponding behaviour, we then reach a better understanding of the relationship between pilot whale sound and pilot whale behaviour.

Whistle detection and classification for whales based on convolutional neural networks

“…Compared with the existing methods presented in Section 1, the proposed method shows a better classification performance for both whale species. Moreover, although the proposed method is used here for whistle detection and classification of only killer whales and long-finned pilot whales, it is not limited to this application and can be easily adapted for other whale or dolphin species that can produce whistles or other sounds; it can also be employed to perform some preliminary work in passive acoustic observation applications for whale or dolphin species, such as range and seasonal occurrence measurement, abundance estimation, and population structure determination, together with some bio-inspired underwater detection or communication systems [32][33][34][35][36][37][38][39].…”

A Basic Bio-Inspired Camouflage Communication Frame Design and Applications for Secure Underwater Communication Among Military Underwater Platforms

“…Second, whale or dolphin groups can produce multiple types of sounds, such as whistles, pulsed calls and clicks [39]. They rely on sound production and reception to travel cooperatively, communicate with each other, convey coordination of behavioral interactions between them and hunt cooperatively in dark or murky waters [40]. In other words, there exists a high-efficiency communication network inside the whale or dolphin groups depending on the sound wave.…”

“…Killer whales echolocate by producing clicks, which are produced in series, quite variable in structure and have frequency peaks between 0.5 to 30 kHz [39], [40]. Click duration range from 0.1 to 20ms, and click repetition rates from a few to over 300 per second [39], [40]. There are abundant colorful and distinct whistles and pulsed calls in killer whales' call pulse trains.…”

“…Whistles are characterized by a continuous waveform, which appears on a time-frequency (TF) spectrum as a call tone with little or no harmonic or side-band structure. The frequency of whistles ranges from about 1.5 to 18 kHz, with peak energy at 6 to 12 kHz [39], [40]. Whistle durations range from 50ms to 12s, and most contained a number of modulations or abrupt shifts in frequency.…”

Synthesis and Modification of Cetacean Tonal Sounds for Underwater Bionic Covert Detection and Communication

“…Based on this criterion, it can be seen that the tonal sound T_up1 is wideband. Therefore, the wideband ambiguity function (WAF) [40]- [42] is used to examine the four key indicators above. The WAF can be defined as follows…”