EDITORS: Hardcastle, William J.; Hewlett, Nigel
TITLE: Coarticulation
SUBTITLE: Theory, Data and Techniques
PUBLISHER: Cambridge
YEAR: 2006
Miguel Ayerbe, Department of English and German Philology, University of the
Basque Country, Spain.
SUMMARY
The book is a collection of studies carried out by different authors on the
phenomenon of coarticulation and is divided into several sections according to
the point of view from which coarticulation is analyzed.
The first two chapters of the book address the phenomenon of coarticulation from
a theoretical perspective. In the first, ''The origin of coarticulation'' by
Barbara Kühnert and Francis Nolan, the concept of coarticulation is introduced
in different ways: First, a definition of coarticulation is provided as ''the
fact that a phonological segment is not realized identically in all
environments, but often apparently varies to become more like an adjacent or
nearby segment'' (page 7). How coarticulation works is also described through
examples drawn from English. Several aspects of coarticulation are discussed
here such as the question of why phonemes are not realized discretely and
invariantly just as they are. The vocal tract is compared with the mechanism of
old typewriters having a separate hammer to produce each single letter, the main
difference being that the vocal tract is always producing in real time and it
articulators cannot move instantaneously from one target configuration such as
the realization of the phoneme /b/ to the next, for example the realization of
/a:/. This is because articulators need time to move from the articulation of
one sound to the articulation of the next and this time period can vary
depending on the similarity of the target configurations between adjacent sounds.
The presentation follows a historical perspective. The phenomenon of
coarticulation was already known before experimental techniques were used at the
end of the nineteenth century. Nevertheless the phenomenon by which speech
sounds influence each other receives the name 'coarticulation' for the first
time in Menzerath and de Lacerda (1933). Later on the study of coarticulation
became a major area of research in the late 1960s with the works of Kozhevnikov
and Chistovich (1965), Öhman (1966), Bladon and Al-Bamerni (1976) with their
concept of 'coarticulation resistance', Kent and Minifie (1977), among others.
In Farnetani and Recasens' contribution, ''Coarticulation models in recent speech
production theories'', the aim of coarticulation models is discussed by
distinguishing them from so-called coarticulation theories, whose aim is to
explain the origin, nature and function of coarticulation. Coarticulation
models, on the contrary, try to predict the processes through which abstract and
discrete units and articulation and acoustics are brought together. According to
the authors two aspects are crucial in testing the predictions of coarticulatory
models: on one hand the ''temporal domain of coarticulation'' and on the other
hand the ''outcome of gestural conflict'' (p. 32).
Following this, different coarticulation theories and models are discussed in
detail such as the theory of Adaptive Variability (Lindblom 1983, 1989, 1990),
Öhman's (1966, 1967) vowel-to-vowel coarticulation model, the theory of feature
spreading developed by Daniloff and Hammearberg (1973), the coarticulation
resistance model introduced by Bladon and Al-Bamerni (1976), Keating's (1985,
1988, 1990) window model, the anticipatory coarticulation model prposed by
Bell-Berti and Harris (1979, 1981, 1982), among others. After the introduction
of each model or theory some comments follow in which their advantages are
described and where they are also confronted with criticism from other authors.
The contributions in Part II are devoted to the description of the function of
different components of the motor system of speech. Chafcouloff and Marchal
(''Velopharyngeal coarticulation'') discuss how nasal features spread onto
adjacent segments. This influencing process is analyzed from two points of view,
on the one hand from contextual effects, i.e. how a nasal sound influences other
segment or segments, and on the other hand from a directional effect, i.e. the
direction and extent of nasal features found in other segments. After providing
physiological, acoustic and perceptual evidence for the influence of nasal
sounds the authors address the direction in which nasality produces its greatest
effects in order to determine whether anticipatory or carryover coarticulation
prevails in the spread of nasal features to neighbouring sounds.
At the end of their contribution Chafcouloff and Marchal point out certain
weaknesses in this field which should be given more attention in future
research. Just to mention one, the authors claim that more attention should be
given to suprasegmental factors such as stress and speech rate, when studying
how nasality influences other segements.
In Chapter Four, ''Lingual coarticulation'', Recasens deals with lingual
coarticulation from the viewpoint of articulatory control of speech production.
The author presents a hypothesis regarding the extent to which articulatory
control by the speaker affects the degree of coarticulatory variability
exhibited in a given region of the tongue (p. 80). The variability of lingual
coarticulation is analyzed from a spatial and from a temporal perspective in
order to see context-dependent effects during the production of lingual gestures
for vowels and consonants. This chapter discusses the influence on
coarticulatory sensitivity of prosodic factors such as syllable position. The
question here is to determine to what extent the position within the syllable
may affect the coarticulatory sensitivity of consonants. According to Recasens
(p. 102) there are consonants that are more sensitive in syllable-final than in
syllable-initial position while others such as [l] are less sensitive in this
position (for English and Catalan) than in syllable-initial position. Other
prosodic factors described by the author are stress, speech rate, segmental
duration and syntactic and phonological boundaries.
Chapter Five, '' Laryngeal coarticulation'', deals with laryngeal coarticulation
in two sections. In the first, Hoole addresses the spatial and temporal
organization of the laryngeal devoicing gesture by considering the
interarticulatory organization of consonantal sequences; in the second, Gobl and
Ní Chasaide deal with the variations which may be found in the vowel's mode of
phonation depending on neighboring consonants. There the stressed vowel
following and preceding phonologically voiceless and voiced consonants such as
/p(:), b(:), v(:), f(:)/ are analyzed in languages like English, German,
Swedish, French and Italian.
Farnetani talks about labial coarticulation in Chapter Six, ''Labial
coarticulation''. In the first part, after indicating that lips are easily
observable compared with other articulators when they move, he discusses the
role of lips in speech production. Then he describes labial articulation from a
phonological and from an articulatory perspective, including a brief anatomical
survey of the facial muscles responsible for labial articulation. Of course this
part deals also with the acoustics and perception of lip rounding. The second
part is devoted to spatial and temporal aspects of labial coarticulation. Here
the author takes as a basis former studies carried out in languages such as
French, English, Swedish and Italian. One of Farnetani's conclusions is that
although there are many experimental studies on labial articulation in several
languages, research work is needed concerning the relation of coarticulation and
cross-language differences in vowel articulation and the phonological function
of lip rounding.
Farnetani's contribution is to some extent continued by Fletcher and
Harrington's study concerning lip and jaw coarticulation. Beginning with a very
brief survey of former investigations dealing with jaw movements as well as the
analysis techniques used such as cinefluorography, X-ray microbeam and
optoelectronic devices, and the role of the jaw in producing vocalic and
consonantal sounds, the author discusses the movement of the mandible and lips
in a vertical dimension. These two relatively independent organs nevertheless
show compensatory and coordinative behavior during speech production. This study
is carried out again from the viewpoint of spatial effects, concerning the
vertical position of the jaw and lip aperture on the one hand, and from the
perspective of temporal effects on the other by describing the relative timing
of successive gestures and related spatial modifications. Finally, he demands
further research on body gestures and for an increasing use of magnetometer and
other articulator tracking devices in order to provide broader analysis of the
spatio-temporal patterning of tongue-body and jaw articulation under the
influence of contextual effects.
Part III ''Wider perspectives'' of coarticulation consists of two contributions.
The first, by Manuel (''Cross-language studies: relating language-particular
coarticulation patterns to other language-particular facts''), focuses on
cross-language studies; the second, by Beckman (''Implications for phonological
theory''), tries to subsume two broad questions concerning the interaction with
phonological theory: to what extent phonological models and representations
developed for other purposes can help our understanding of the coarticulatory
patterns described in the previous chapters; and what coarticulatory patterns
imply about the shape of phonological models and representations.
Part IV is devoted to different instrumental techniques used in coarticulatory
analysis, their history, development, advantages and limits.
In Chapter Ten, ''Palatography'', Gibbon and Nicolaidis describe palatographic
techniques, such as EPG. After introducing different EPG systems developed in
Great Britain, Japan and America they describe the so-called artificial palate
and how it is used, providing some illustrations from different models. They
also show what results look like as well as how data obtained are to be
interpreted. In addition it must be said at this point that while EPG analysis
provides very useful data for articulatory and coarticulatory research, thought
must be given to the costs derived from the elaboration of the artificial
palate. These must be adapted to the vocal tract of the speaker but each speaker
has a different anatomical configuration of his/her vocal tract and this means
that each speaker needs a particular artificial palate. But this is not a
problem in itself, but it comes with a price.
Imaging techniques are the subject of Stone's contribution (''Imaging
techniques''). Techniques such as lateral x-ray, computed tomography, magnetic
resonance imaging and ultrasound are described. Then the applications of imaging
techniques for the study of coarticulation are discussed. One of the advantages
of these techniques is the fact that they allow vocal tract behavior to be shown
during speech.
In Chapter Twelve, ''Electromagnetic articulography'', Hoole and Ngyen describe
electromagnetic articulography (also known as EMMA - Electromagnetic Midsagittal
Articulography), its properties, measurement principle and source errors,
environmental conditions and possible combinations with other equipment and
interference with the subject's articulation. A special section concerns safety
regulations regarding the use and exposure to electromagnetic radiation, by
presenting the guidelines of The International Radiation Protection Association,
published 1990, as well as some other relevant safety indications.
In Chapter Thirteen, ''Electromyography'', Hardcastle takes another direction by
describing Electromyography. Compared with previous instrumental techniques,
which record the activity of articulatory components whether respiratory,
laryngeal or supralaryngeal, electromyography provides data from the underlying
neuromuscular control mechanisms that make these movements possible as well as
the patterns of contraction and relaxation of particular muscles or muscle groups.
In the following chapter, ''Transducers for investigating velopharyngeal
function'', Chafcouloff introduces several instrumental techniques for the study
of nasalization and the velopharingeal function. These are divided into two
groups: The first covers indirect observation techniques such as aerometry,
electromyography, and acoustics; the second concerns direct observation
techniques such as radiography, endoscopy, photodetection, mechanical devices
and others such as ultrasound, magnetic resonance imaging and electromagnetic
articulometry.
Chapter Fifteen, ''Techniques for investigating laryngeal articulation'', is
devoted to techniques for investigating laryngeal articulation. This chapter is
divided into two sections: section A by Hoole concerns laryngeal adjustments of
abduction and adduction involved in the production of voiceless segments, also
known as 'devoicing gestures'; in section, B Gobl and Ní Chasaide focus on a
detailed acoustic analysis of phonation.
Chapter Sixteen, ''Acoustic analysis'', is devoted to techniques for acoustic
analysis, which in these days have developed considerably with the result that
they now allow a more detailed analysis of larger amounts of data. Recasens
discusses different methods and the concrete techniques they are used for. He
also draws attention to analysis fields such as segmentation, coarticulatory
effects between adjacent segments at the acoustic level and coarticulation not
involving non-adjacent phonetic segments.
EVALUATION
In general and in particular I may congratulate the editors and contributors.
The structure and organization of the book is really surprising and
illustrating. The different contributions cover all important questions
concerning the phenomenon of coarticulation in the production of speech by
dividing the book into four clearly defined parts, such as theoretical aspects
and the definition of coarticulation, components of the motor system for speech
where each component is described in detail, other perspectives concerning
forthcoming research work in coarticulation, and finally different instrumental
techniques used for investigating coarticulation effects.
Each chapter is well organized, beginning with an introduction to the field.
After discussing previous scientific literature concerning the subject of each
chapter the author describes in a very clear and illuminating manner how
analysis is carried out as well as the limits and problems.
To sum up, not only is the whole book very complete but each contribution
provides a rich amount of interesting and useful information that covers all
aspects needed for a very good survey of what has been done before, what is
being done now as well as what still remains to be done in the field of
coarticulation. As well as that all techniques used for analysis are presented
and also how data have to be interpreted. This all makes of this book a very
useful tool not only for phoneticians and other scientists but also for people
who do not have much basic knowledge of coarticulation. Therefore I strongly
recommend it to undergraduate students of Linguistics, Phonetics and Phonology.
REFERENCES
Bladon, R.A.W. & A. Al-Bamerni. (1976) Coarticulation resistance in English /l/.
_Journal of Phonetics_ 4, pp.137-150.
Kent, R. & F. Minifie. (1977) Coarticulation in recent speech production models.
_Journal of Phonetics_ 5, pp. 115-133.
Kozhevnikov, V. & L. Chistovich. (1965) _Speech: Articulation and Perception_.
Washington: Joint Publications Research Service.
Menzerath, Paul & Antonio de Lacerda. (1933) _Koartikulation, Steuerung und
Lautabgrenzung_. Berlin and Bonn: Fred. Dummlers.
Öhman, S. (1966) Coarticulation in VCV utterances: spectrographic measurements.
_Journal of the Acoustical Society of America_ 58, pp. 151-168.
ABOUT THE REVIEWER
Miguel Ayerbe has studied German Philology in Seville and Cologne. He became PhD
in 2004, after working in Seville and Munich in Historical and Contrastive
Linguistics. He has taught German Historical Grammar in Seville and now, he is
working at the University of the Basque Country (Spain), where he teaches German
Phonetics and Phonology, Morphology and German Historical Grammar. His current
research interests are German contrastive phonetics and phonology.
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