Information theory and the language of the whales
The Acoustic Signal Processing Laboratory, of the School of Marine Sciences and Technology of the University of Massachussets Darthmouth, directed by Assoc. Prof. John R. Buck, has recetly published a number of studies on animal communication, on whales signalling systems and on Zipf's Law applied to non-human communication systems.Specifically the works of R. Suzuki and colleagues deal with the interpretations of the songs of the humpback whale, as the Howard Hughes Medical Institute has recently reported (Warbling Whales Speak a Language All Their Own, March 21, 2006), and on complex syntactic capabilities showed in the signalling behaviour. In the last issue of the Journal of the Acoustical Society of America (119, 3, p. 1849-66) an article on "Information entropy of humpback whale songs" by Ryuji Suzuki, John R. Buck, Peter L. Tyack discusses complexity, redundancy, and predictability of the whales songs, the role of repetition. It is an extremely interesting approach, taking advantage of information theory applied to animal communication.
Some years ago an essey discussing this approach was published by the same team. In the 2003 article Suzuki et alii suggested that Zipf's law is not an appropriate tool for animal communication analysis claiming that: "Tests based on Zipf’s law are highly susceptible to false positives, both in theory and practice." (p. 9) and furthermore that "(1) the Zipf’s distribution model is not an effective way to analyse unknown information sources, even when we know that the source statistics closely follow this distribution; (2) Zipf’s law analysis cannot reliably discriminate between languages and stochastic processes devoid of semantic or communicative content. Studies that have depended on Zipf’s law as a language detector or to measure communication capacity should develop alternative techniques." (p. 16). Particularly interesting the implication on redundancy principle in the psychobiological perspective.
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Suggested readings:
> R. Suzuki, J. R. Buck, and P. L. Tyack, "The use of Zipf's law in animal communication analysis," Animal Behaviour, January 2005, Vol. 69. pp. F9-F17. (Paper Download: PDF)
> R. Suzuki, J. R. Buck, and P. L. Tyack, "Information entropy of humpback whale songs", Journal of the Acoustical Society of America, 119, 3, p. 1849-66.
> Songs of the humpback whales, recorded in Hawaii. Listen
> I. Chiari, Ridondanza e linguaggio, Roma: Carocci.
