Dear All,
We are pleased to announce the publication of a new paper in Journal of the Acoustical Society of America:
Variability of the inter-pulse interval in sperm whale clicks with implications for size estimation and individual identification
By: Anne Bøttcher, Shane Gero, Kristian Beedholm, Hal Whitehead & Peter T. Madsen
The paper is available here: https://asa.scitation.org/doi/10.1121/1.5047657
or PDFs by request from the authors.
Sperm whales generate multi-pulsed clicks for echolocation and communication with an inter-pulse interval (IPI) determined by the size of their hypertrophied sound producing nose. The
IPI has therefore been used to estimate body size and distinguish between individuals, and it has been hypothesized that conspecifics may use IPIs to recognize each other. However, the degree to which IPIs vary within individuals has not explicitly been tested,
and therefore the inherent precision of this measure and its applicability for size estimation for researchers and sperm whales alike remain unknown. Here, the variability in IPI from both animal-borne Dtags and far-field recordings from echolocating and communicating
sperm whales is quantified. Three different automatic methods (envelope, cepstrum, and cross-correlation) are tested and it is found that the envelope approach results in the least dispersion. Furthermore, it is shown that neither growth, depth, nor recording
aspect fully explains the observed variability among clicks recorded from the same individual. It is proposed that dynamics in the soft structures of the nose are affecting IPIs, resulting in a variation of approximately 0.2 ms. Therefore, it is recommended
that this variation be considered in IPI studies and that IPIs may have limited functionality as an identity cue among large groups of conspecifics.
My very best,
Shane
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Assistant Professor Founder | Principal Investigator
Marine Bioacoustics Lab
The Dominica Sperm Whale Project
Institute for Bioscience Find us on
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