The encoding of individual identity in dolphin signature whistles: how much information is needed?

Arik Kershenbaum, Laela Sayigh, Vincent M. Janik

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)
3 Downloads (Pure)

Abstract

Bottlenose dolphins (Tursiops truncatus) produce many vocalisations, including whistles that are unique to the individual producing them. Such “signature whistles” play a role in individual recognition and maintaining group integrity. Previous work has shown that humans can successfully group the spectrographic representations of signature whistles according to the individual dolphins that produced them. However, attempts at using mathematical algorithms to perform a similar task have been less successful. A greater understanding of the encoding of identity information in signature whistles is important for assessing similarity of whistles and thus social influences on the development of these learned calls. We re-examined 400 signature whistles from 20 individual dolphins used in a previous study, and tested the performance of new mathematical algorithms. We compared the measure used in the original study (correlation matrix of evenly sampled frequency measurements) to one used in several previous studies (similarity matrix of time-warped whistles), and to a new algorithm based on the Parsons code, used in music retrieval databases. The Parsons code records the direction of frequency change at each time step, and is effective at capturing human perception of music. We analysed similarity matrices from each of these three techniques, as well as a random control, by unsupervised clustering using three separate techniques: k-means clustering, hierarchical clustering, and an adaptive resonance theory neural network. For each of the three clustering techniques, a seven-level Parsons algorithm provided better clustering than the correlation and dynamic time warping algorithms, and was closer to the near-perfect visual categorisations of human judges. Thus, the Parsons code captures much of the individual identity information present in signature whistles, and may prove useful in studies requiring quantification of whistle similarity.
Original languageEnglish
Article numbere77671
JournalPLoS One
Volume8
Issue number10
DOIs
Publication statusPublished - 23 Oct 2013

Keywords

  • Bottlenose dolphin
  • Signature whistles
  • Individual recognition
  • Identity information
  • Social influences
  • Parsons code
  • Frequency measurements
  • Clustering algorithms

Fingerprint

Dive into the research topics of 'The encoding of individual identity in dolphin signature whistles: how much information is needed?'. Together they form a unique fingerprint.

Cite this