Table Of Content

DYNAMICS OF SPEECH PRODUCTION AND PERCEPTION NATO Science Series A series presenting the results of scientific meetings supported under the NATO Science Programme. The series is published by IOS Press and Springer Science and Business Media in conjunction with the NATO Public Diplomacy Division. Sub-Series I. Life and Behavioural Sciences IOS Press II. Mathematics, Physics and Chemistry Springer Science and Business Media III. Computer and Systems Sciences IOS Press IV. Earth and Environmental Sciences Springer Science and Business Media V. Science and Technology Policy IOS Press The NATO Science Series continues the series of books published formerly as the NATO ASI Series. The NATO Science Programme offers support for collaboration in civil science between scientists of countries of the Euro-Atlantic Partnership Council. The types of scientific meeting generally supported are “Advanced Study Institutes” and “Advanced Research Workshops”, although other types of meeting are supported from time to time. The NATO Science Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s Partner countries – countries of the CIS and Central and Eastern Europe. Advanced Study Institutes are high-level tutorial courses offering in-depth study of latest advances in a field. Advanced Research Workshops are expert meetings aimed at critical assessment of a field, and identification of directions for future action. As a consequence of the restructuring of the NATO Science Programme in 1999, the NATO Science Series has been re-organized and there are currently five sub-series as noted above. Please consult the following web sites for information on previous volumes published in the series, as well as details of earlier sub-series: http://www.nato.int/science http://www.springeronline.nl http://www.iospress.nl http://www.wtv-books.de/nato_pco.htm Series I. Life and Behavioural Sciences – Vol. 374 ISSN: 1566-7693 Dynamics of Speech Production and Perception Edited by Pierre Divenyi Veterans Affairs Medical Center and East Bay Institute for Research and Education, Martinez, California, USA Steven Greenberg Silicon Speech, Santa Venetia, California, USA and Georg Meyer Liverpool University, UK Amsterdam • Berlin • Oxford • Tokyo • Washington, DC Published in cooperation with NATO Public Diplomacy Division Proceedings of the NATO Advanced Study Institute on Dynamics of Speech Production and Perception Il Ciocco (Lucca), Italy 23 June – 6 July 2006 © 2006 IOS Press. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without prior written permission from the publisher. ISBN 1-58603-666-1 Library of Congress Control Number: 2006932184 Publisher IOS Press Nieuwe Hemweg 6B 1013 BG Amsterdam Netherlands fax: +31 20 687 0019 e-mail: [email protected] Distributor in the UK and Ireland Distributor in the USA and Canada Gazelle Books Services Ltd. IOS Press, Inc. White Cross Mills 4502 Rachael Manor Drive Hightown Fairfax, VA 22032 Lancaster LA1 4XS USA United Kingdom fax: +1 703 323 3668 fax: +44 1524 63232 e-mail: [email protected] e-mail: [email protected] LEGAL NOTICE The publisher is not responsible for the use which might be made of the following information. PRINTED IN THE NETHERLANDS To Ludmilla’s memory vi In Memoriam Ludmilla Andreevna Chistovich 1924 - 2006 vii This book is dedicated to the memory of Ludmilla A. Chistovich. Her pioneering research blazed an important path for the scientific investigation of speech that many others have followed in recent years. As the founder of the “Leningrad School” (along with her husband, Valeriy A. Kozhevnikov) she headed one of the most dynamic and creative groups investigating the production and perception of speech. The influence of Chistovich and her colleagues has been profound, as many of the chapters in this volume attest. Her work was among the first to integrate nonlinear dynamics into models of speech production and perception. She was also among the first to appreciate the importance of auditory nonlinearities for the neural representation of speech. Ludmilla Chistovich was born in Leningrad in 1924. She trained as a medical doc- tor prior to her research career at the Pavlov Institute of Physiology in Leningrad. In 1960, she founded the Laboratory of Speech Physiology at the Pavlov Institute. At the same time, Valeriy Kozhevnikov established the Laboratory of Speech Biophysics. The two worked in close collaboration until Kozhevnikov’s untimely death 20 years later. The group’s early research was summarized in a monograph entitled Speech: Artic- ulation and Perception, a translation from the Russian of Rech: Artikulyatsiya i Vospriyatiye (Moscow-Leningrad, 1965). This book introduced what were radical con- cepts for the time: nonlinear dynamics, the syllable as a basic unit of production and perception, and the importance of studying production and perception as reflections of a single, integral process. In 1976, a second monograph was published: Speech Physiol- ogy and Speech Perception by Man (in Russian). This book was one of the first attempts to apply a comprehensive approach to speech research, integrating phonetics, psychoa- coustics, physiology signal processing and modeling. Although this interdisciplinary approach is common today, it represented a radical departure from the way in which speech was studied in the 1970s. Given all that she and her group accomplished, Ludmilla Chistovich was entitled to retire to a life of ease and relaxation. Instead, after her official retirement in 1986, she began a second career, this one focused on developing social charities and public inter- est organizations. It was the era of “perestroika,” and many things were changing in the Soviet Union. Chistovich was among the founders of the Mercy Society, the first chari- table organization established in the former USSR. She also founded the Leningrad Consumers Society, where she oversaw the department concerned with the rights of ill and disabled individuals. As part of her efforts, she organized an important conference on the topic of the sick and disabled, which was the beginning of Leningrad’s publicly funded programs for the elderly and young. In 1991, Chistovich, together with her daughters Elena Kozhevnikova and Inna Chistovich, established the St. Petersburg Early Intervention Institute (EII, http://www.eii.ru). The EII was set up as a means of fostering the language development of young children through providing auditory screening in infants and early intervention programs for hearing-impaired children. During the last years of her life, Ludmilla Chis- tovich worked with EII to establish early intervention programs in other locations, first in St. Petersburg and eventually throughout Russia and other parts of the former Soviet Union. She passed away on April 11, 2006, shortly before this book went to press. Additional information about Ludmilla Chistovich’s scientific accomplishments can be found in Speech Communication, Volume 4 (1985) as well as http://www.mind- spring.com/~rjporter/SeattlePavlovRev.htm. This page intentionally left blank Dynamics of Speech Production and Perception ix P. Divenyi et al. (Eds.) IOS Press, 2006 © 2006 IOS Press. All rights reserved. Preface “Natural speech is not a simple sequence of steady-state segments. To represent the speech signal, as perceived by the listener, as if it were a succession of discrete segments (analogous to alphabetic characters) or even as a sequence of phonetically meaningful elements is simplistic at best. It is only possible to portray speech as a succession of elements when the ensemble of complex information transformations that comprise speech perception are fully taken into account.” Ludmilla Chistovich [1, p.10] That speech is a dynamic process strikes as a tautology: whether from the standpoint of the talker, the listener, or the engineer, speech is an action, a sound, or a signal continu- ously changing in time. Yet, because phonetics and speech science are offspring of clas- sical phonology, speech has been viewed as a sequence of discrete events-positions of the articulatory apparatus, waveform segments, and phonemes. Although this perspec- tive has been mockingly referred to as "beads on a string" [3], from the time of Henry Sweet's 19th century treatise [5] almost up to our days specialists of speech science and speech technology have continued to conceptualize the speech signal as a sequence of static states interleaved with transitional elements reflecting the quasi-continuous nature of vocal production. After all, there must be static, stable elements internally if listeners can perceive and label individual phonemes in the speech stream. While this discrete representation-static targets reached during production and recovered during perception-may describe, at best, clearly pronounced "hyper" speech in which departures from the canonical are rare, it badly fails to characterize spoken language where such departures constitute the norm. A good example for the inadequacy of phonemic representation is a recent analysis of 45 minutes of spontaneous conversational speech in which 73 different forms of the word "and" were seen, and yet all of them were unambiguously identified by listeners [2]. Obviously, we need to part with the phoneme as the basic unit of speech if we want to study verbal communication. Fortunately, an alternative approach was developed in the latter half of the twentieth century by a team of scientists at the Pavlov Institute of Physiology in St. Petersburg, the then-Leningrad. Headed by Ludmilla Chistovich and her husband Valeriy Kozhevnikov, two great pioneers of speech research, this remarkable team recognized that even in clear speech the phoneme could not be considered without the context in which it appeared. In their view, the phoneme was an epiphenomenon, derived from the more basic unit of the syllable [1]. In this, as in so many aspects of speech models, the so-called "Leningrad group" was far ahead of its time. In the groundbreaking volume "Speech: Articulation and Perception," [4] this group introduced the concept of dynamic systems to speech research-as early as in the mid-1960s. For decades, their research was considered more of an exotic curiosity than serious work because of its unusual and dis-