Rhythmic dimension in the echolocation click trains of sperm whales: a possible function of identification and communication
Fourier spectral analysis was used to highlight a rhythmic dimension of the click repetition pattern of the sperm whale ( Physeter macrocephalus ). Analysis of numerous series of regular clicks only showed occasionally the previously described codas used for communication. Out of a sample recording...
Published in: | Journal of the Marine Biological Association of the United Kingdom |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
2000
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Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s002531549900168x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002531549900168X |
Summary: | Fourier spectral analysis was used to highlight a rhythmic dimension of the click repetition pattern of the sperm whale ( Physeter macrocephalus ). Analysis of numerous series of regular clicks only showed occasionally the previously described codas used for communication. Out of a sample recording of vocalizing sperm whales, an apparent cacophony, belonging to a year-round resident group foraging a few miles off the coast of Gran Canaria, the individual click sequences of four animals have been unravelled by cross-correlating their time wave shapes. The Fourier spectrum, which yields the harmonic aspects of each isolated click sequence, shows a deterministic structure that appears as a strong modulating frequency. This shows that click production is not a random process and possibly characterizes, in fact, a signature of the animal. Here we introduce a new concept: this rhythmic modulation represents the acoustic signature of each individual sperm whale, which we have called RIME (rhythmic identity measurement). The RIME would allow a whale to distinguish its own echo time pattern from the background of other click trains during echolocation. The RIME appears to represent a new concept in communication strategies and might also be present in other-social-odontocete repertoires. |
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