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THE ORIGINS OF SPEECH SOUNDS
What is the origins of vowels and consonants? How can a
society of individuals develop and share a system of sounds ? Why some
vowels and consonants are so frequent in human languages and some other so
rare?
These are the questions I am interested in. The hypothesis I am studying is that the origins of speech can be understood only as the result of complex dynamical interactions between speaking and listening individuals, each of them being a complex system in which the vocal tract, the ear, and the neural system that connects them are coupled.
The dynamics of complex systems is difficult to understand,
and one of the best tools to study them is computer modeling. This is why
I have been building societies of artificial agents endowed with
artificial vocal tracts, ears and brains, in order to explore the possible
mechanisms that could explain the origins of shared speech systems.
Through these computational experiments, I
have shown that from a minimal neural kit for vocal replication, a shared
combinatorial speech code with structural regularities and diversity can
spontaneously self-organize in a population of agents. This allows to
understand that the evolutionary step from vocal replication systems to
modern human speech systems might have been rather small.
The aim of these
experiments is not to prove directly
what mechanisms were used for humans, but rather to develop our intuitions
and to help structuring the research debate. In particular, building
artificial systems allows us to shape the search space of possible
answers, in particular by showing what is sufficient and what is not
necessary.
I wrote a book describing the results of my research in evolutionary phonology: Oudeyer, P-Y. (2006) Self-Organization in the Evolution of Speech, Studies in the Evolution of Language, Oxford University Press. (Translated by James R. Hurford). My main papers on this subject: 1) The three following papers
summarize the main results of a recent model in which ears and vocal
tracts are coupled with simple neural maps. The first one shows how the
coupling of babbling agents produces a shared system of syllable system at
the population level, and how discreteness in syllable systems can appear: The second paper describes how combinatoriality, i.e. phonemic coding, and basic rules of phonotactics can form: Oudeyer, P-Y. (2005) The self-organisation of combinatoriality and phonotactics in vocalization systems, Connection Science, vol. 17, No. 3, pp. 1-17. The third one provides an evolutionary interpretation of the computational models developed in the two previous papers, basically arguing that evolutionary step from analogic and basic vocal imitation to shared combinatorial speech codes might have been rather small: Oudeyer, P-Y. (2007) From vocal replication to shared combinatorial speech codes: a small step for evolution, a big step for language, In Lyon, C., Nehaniv L. and A. Cangelosi, editor, Emergence of Communication and Language, pp. 207--222, Lecture Notes in Computer Science, Springer-Verlag. Berlin. bibtex reference
2) Another model which I developed showed how syllable systems constructed through cultural evolution could become adapted to the cognitive constraints of speakers and listeners: syllable systems were culturally selected for learnability. This work was based on an extensions of Bart de Boer's work on vowel systems to syllable systems. Oudeyer, P-Y (2005) How phonological structures can be culturally selected for learnability, Adaptive Behavior, 13(4), pp. 269--280. bibtex reference A related and more general paper: Oudeyer P-Y., Kaplan F. (2007) Language Evolution as a Darwinian Process: Computational Studies, Cognitive Processing, , 8(1), pp. 21--35. DOI: 10.1007/s10339-006-0158-3. 3) In french: Oudeyer, P-Y. (2005) Aux sources du langage : l'auto-organisation de la parole, Cahiers Romans de Sciences Cognitives, Cuadernos Romances de Ciencias Cognitivas, Cadernos Românicos em Ciências Cognitivas, Quaderni Romanzi di Scienze Cognitive, In Cognito, 2 (2), pp. 1--24.
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MY BOOK
Self-Organization in the Evolution of Speech, Oxford University Press
RELATED PROJECTS
The Maïdo and Gurby Experiment
Acquisition and evolution of language
Developmental Robotics and Artificial Curiosity
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