edinburgh university press clinical linguistics sep 2008

Clinical Linguistics
Louise Cummings
The Royal College of Speech and Language Therapists estimates that 2.5 million people
in the UK have a communication disorder. Of this number, some 800,000 people have
a disorder that is so severe that it is hard for anyone outside their immediate families
to understand them. In
Clinical Linguistics, Louise Cummings examines the various
developmental and acquired communication disorders that constitute these large
and growing figures. In chapters that are dedicated to the discussion of individual
communication disorders, Cummings argues that no treatment of this area can
reasonably neglect an examination of the prevalence and causes of communication
disorders.The assessment and treatment of these disorders by speech and language
therapists are discussed at length.This book contains up-to-date research into
communication disorders and describes the various technological innovations that are
integral to the work of speech and language therapists.
Clinical Linguistics is appropriate reading for students, practitioners and researchers in
speech-language pathology and related clinical and academic disciplines. It contains the
following chapters:The Scope of Clinical Linguistics; Disorders of the Pre- and Perinatal
Period; Disorders of Cognitive Development; Disorders of Speech and Language
Development;Acquired Communication and Swallowing Disorders; Disorders of
Fluency;
Disor
ders of
V
oice.
Louise Cummings is a Reader in Linguistics, Nottingham Trent University. She is a
member of the Ro
yal College of Speech and Language Therapists and is registered
with the Health Professions Council.
‘
Clinical Linguistics by Louise Cummings is a monumental undertaking. Cummings

covers the discipline, from child language and speech disorders to failed communication
in adulthood. Further, she covers each of the disorders comprehensively, from its
biology and its medical features to its epidemiology; from assessment to treatment.
And it is all done with a sound and disciplined scholarship.This almost encyclopedic
text is even-handed and fair, focusing on the disorders and the individuals who have
them, rather than on professional opinions concerning effective treatment. It is truly
breathtaking, in scope and in consistency of purpose. I really can't think of anything
like it.’
Audrey L. Holland, Regents’ Professor Emerita, University of Arizona.
Cover design: www.riverdesign.co.uk
Cover image: Magnetic resonance 2 © iStockphoto, 2007
Edinburgh Univ
ersity Pr
ess
22 George Square, Edinburgh EH8 9LF
www.eup.ed.ac.uk
ISBN 978 0 7486 2077 7
Louise Cummings
Edinburgh
barcode
Louise Cummings
Clinical Linguistics
Clinical Linguistics
Clinical Linguistics
In memory of a dear friend
Jacqueline Elizabeth Henry (née McCormick)
23.3.1971 ~ 24.1.2001
Clinical Linguistics
Louise Cummings
EDINBURGH UNIVERSITY PRESS

© Louise Cummings, 2008
Edinburgh University Press Ltd
22 George Square, Edinburgh
Typeset in 11/13 Ehrhardt MT and Gill Sans
by Servis Filmsetting Ltd, Manchester, and
printed and bound in Great Britain by
Antony Rowe Ltd, Chippenham, Wilts
A CIP record for this book is available from the British Library
ISBN 978 0 7486 2076 0 (hardback)
ISBN 978 0 7486 2077 7 (paperback)
The right of Louise Cummings
to be identified as author of this work
has been asserted in accordance with
the Copyright, Designs and Patents Act 1988.
Contents
List of Figures and Tables ix
Acknowledgements xi
Preface xiii
1 THE SCOPE OF CLINICAL LINGUISTICS 1
1.1 A New Definition of an Established Practice 1
1.2 Human Communication: Processes 2
1.3 Human Communication: Disorders 4
1.4 The Contribution of Linguistic Science 7
1.5 The Contribution of Medical Science and its Practitioners 12
1.6 The Purpose of Structure 17
1.6.1 Epidemiology and Aetiology 18
1.6.2 Clinical Assessment 19
1.6.3 Clinical Intervention 21
Notes 23
2 DISORDERS OF THE PRE- AND PERINATAL PERIOD 27

2.1 Introduction 27
2.2 Cleft Lip and Palate 28
2.2.1 Epidemiology and Aetiology 28
2.2.2 Clinical Assessment 38
2.2.2.1 Feeding 39
2.2.2.2 Speech 41
2.2.2.3 Hearing 50
2.2.2.4 Language 55
2.2.3 Clinical Intervention 60
v
2.2.3.1 Surgical Intervention 60
2.2.3.2 Speech and Language Intervention 63
2.3 Cerebral Palsy 70
2.3.1 Epidemiology and Aetiology 71
2.3.2 Clinical Assessment 75
2.3.2.1 Feeding 76
2.3.2.2 Speech 81
2.3.2.3 Hearing 87
2.3.2.4 Language 89
2.3.3 Clinical Intervention 92
2.3.3.1 Feeding Intervention 93
2.3.3.2 Communication Intervention 99
Notes 110
3 DISORDERS OF COGNITIVE DEVELOPMENT 129
3.1 Introduction 129
3.2 Learning Disability 130
3.2.1 Epidemiology and Aetiology 131
3.2.2 Clinical Presentation 138
3.2.2.1 Feeding 138
3.2.2.2 Speech 141

3.2.2.3 Hearing 149
3.2.2.4 Language 152
3.2.3 Clinical Intervention 160
3.2.3.1 Early Communication Intervention 161
3.2.3.2 Speech and Language Intervention 165
3.2.3.3 Augmentative and Alternative
Communication 177
3.3 Autistic Spectrum Disorder 182
3.3.1 Epidemiology and Aetiology 186
3.3.2 Clinical Presentation 192
3.3.2.1 Comorbid Conditions 193
3.3.2.2 Communication Features 197
3.3.3 Clinical Assessment 204
3.3.4 Clinical Intervention 209
Notes 219
4 DISORDERS OF SPEECH AND LANGUAGE
DEVELOPMENT 244
4.1 Introduction 244
4.2 Developmental Verbal Dyspraxia 245
4.2.1 Epidemiology and Aetiology 245
CONTENTS
vi
4.2.2 Clinical Presentation 247
4.2.3 Assessment and Diagnosis 254
4.2.4 Clinical Intervention 259
4.3 Developmental Phonological Disorder 265
4.3.1 Epidemiology and Aetiology 265
4.3.2 Clinical Presentation 267
4.3.3 Phonological Assessment 271
4.3.4 Phonological Intervention 276

4.4 Specific Language Impairment 281
4.4.1 Epidemiology and Aetiology 282
4.4.2 Clinical Presentation 285
4.4.3 Clinical Intervention 293
4.4.4 SLI and Cognitive Deficits 297
4.5 Landau-Kleffner Syndrome 299
Notes 302
5ACQUIRED COMMUNICATION AND
SWALLOWING DISORDERS 310
5.1 Introduction 310
5.2 Acquired Dysarthria 310
5.2.1 Epidemiology and Aetiology 311
5.2.2 Clinical Presentation 317
5.2.3 Dysarthria Assessment 321
5.2.4 Dysarthria Intervention 327
5.3 Apraxia of Speech 331
5.3.1 Epidemiology and Aetiology 331
5.3.2 Clinical Presentation 332
5.3.3 Assessment and Intervention 335
5.4 Acquired Aphasia 341
5.4.1 Epidemiology and Aetiology 342
5.4.2 Clinical Presentation 344
5.4.3 Aphasia Assessment 349
5.4.4 Aphasia Intervention 353
5.5 Acquired Dysphagia 357
5.5.1 Epidemiology and Aetiology 357
5.5.2 Clinical Presentation 358
5.5.3 Dysphagia Assessment 358
5.5.4 Dysphagia Intervention 361
5.6 Schizophrenia 364

Notes 370
CONTENTS
vii
6 DISORDERS OF FLUENCY 378
6.1 Introduction 378
6.2 Stuttering 379
6.2.1 Epidemiology and Aetiology 379
6.2.2 Clinical Presentation 381
6.2.3 Clinical Assessment 385
6.2.4 Clinical Intervention 389
6.3 Cluttering 397
Notes 400
7 DISORDERS OF VOICE 404
7.1 Introduction 404
7.2 Voice Disorders 405
7.2.1 Epidemiology and Aetiology 405
7.2.2 Clinical Presentation 410
7.2.3 Clinical Assessment 411
7.2.4 Clinical Intervention 413
7.2.4.1 Surgery 414
7.2.4.2 Radiotherapy 416
7.2.4.3 Drugs 416
7.2.4.4 Voice Therapy 417
Notes 420
Bibliography 423
Index 498
CONTENTS
viii
List of Figures and Tables
Figures

1.1 The process of communication 4
2.1(A) Frontal view of mouse embryo on day 10 of gestation 30
2.1(B) Fifth week of human gestation 30
2.1(C) Frontal view of mouse embryo on day 11 of gestation 31
2.1(D) Frontal view of human embryo 31
2.1(E) Human embryo during sixth week of gestation 32
2.1(F) A mouse embryo on day 11 of gestation 32
2.1(G) A mouse embryo on day 12 of gestation 33
2.2 The normal lip and nose 34
2.3(A) Frontal view of a mouse embryo on day 14 of gestation 34
2.3(B) Frontal view of a mouse embryo on day 14 of gestation 35
2.3(C) Human embryo in the ninth week of gestation 35
2.4 The normal and cleft palate 36
2.5 The cleft lip and nose 37
2.6 Unilateral and bilateral cleft lip and palate 37
2.7 Primary teeth 39
2.8 Gross structure of the ear 51
2.9 Opening of the Eustachian tube 52
2.10 Ventilating tube in the ear drum 53
3.1 Pictographic and ideographic Blissymbols 178
3.2 Picture Communication Symbols 180
7.1 Anatomical structures after laryngectomy and
postlaryngectomy voice production 415
ix
Ta b l es
1.1 Communication processes and disorders 7
2.1 Kernahan and Stark’s (1958) classification of cleft lip and palate 38
LIST OF FIGURES AND TABLES
x
Acknowledgements

I wish to acknowledge with gratitude the assistance of the following people and
organisations: Kathy Sulik, Karlind T. Moller, InHealth Technologies, Mayer-
Johnson LLC and the Cleft Palate Foundation, for their permission to use a
number of the illustrations that appear in this book; the Tennessee Craniofacial
Center, for its donation of The Craniofacial Surgery Book; Roger Bromley, Liz
Morrish and John Tomlinson, for their provision of a sabbatical and rearrange-
ment of teaching duties; John Wells, for advice on phonetic fonts and Sarah
Edwards of Edinburgh University Press, for accommodating my numerous
requests as the book developed. The assistance of each of these individuals and
organisations has been invaluable.
Much of the research for this book was undertaken while I was a Visiting
Fellow in the Centre for Research in the Arts, Social Sciences and Humanities
(CRASSH) at the University of Cambridge. I am grateful to the Director of
CRASSH, Mary Jacobus, for her support and encouragement. During my time
at Cambridge, Wolfson College provided me with an environment that was
particularly conducive to conducting research. I extend my gratitude to its
President and Fellows.
The task of writing a book is made more manageable when one receives the
assistance of others. I particularly wish to thank Judith Heaney for her careful
preparation of the manuscript. I am also grateful to her husband Stewart for
his work on the numerous diagrams in the following pages. Jo Mills of the
Clifton Audio-Visual Unit at Nottingham Trent University reproduced the
embryology images in chapter 2 and I extend my gratitude to her. Roberta
Davari-Zanjani has assisted me at various stages with the scanning of diagrams
and I thank her for not growing tired of my endless requests. The assistance of
xi
Sian Griffiths and other staff in the Clifton Library of the university is also
gratefully acknowledged.
Finally, I have been supported in this endeavour by family members and
friends who are too numerous to mention individually. I am grateful to them

for their kind words of encouragement during my many months of writing.
ACKNOWLEDGEMENTS
xii
Preface
In recent years, some remarkable developments have taken place in our know -
ledge and management of communication and swallowing disorders in chil-
dren and adults. Some of these developments have come about through work
in medical disciplines: for example, the study of the genetics of specific lan-
guage impairment. Other developments are the result of technological
progress in fields such as computer science and medical diagnostics. One need
only consider the phenomenal growth that has recently occurred in augmen-
tative and alternative communication to appreciate the significance of such
progress for the management of clients with severe communication disorder.
Similarly, the dysphagia clinician and voice therapist rely heavily on these
technological achievements in their assessment and treatment of dysphagic
and dysphonic clients, respectively. Theoretical developments in linguistics
and psychology have also transformed our understanding and management of
communication disorders. The greater prominence of pragmatics within lin-
guistics, for example, has encouraged clinicians to reconsider how language
disorders are assessed and treated – how aphasic adults manage the demands
of different conversational contexts and communicative partners is now as
likely (and, perhaps, even more likely) to be addressed in assessment and inter-
vention as is the comprehension and production of certain syntactic struc-
tures. Psychologists have radically influenced our understanding of the
communicative impairments in autism through their proposal of theories of
the core cognitive deficit in this developmental psychopathology. The theory
of mind proposals of Simon Baron-Cohen and co-workers hold particular
resonance for any speech and language therapist who has witnessed the severe
pragmatic deficits of many children and adults with an autistic spectrum
disorder.

xiii
Clearly, developments which have implications for the study of clinical lin-
guistics have been proceeding apace. In this book, the reader is introduced to
these developments in the context of discussion of specific communication and
swallowing disorders. The latest research findings on these disorders are pre-
sented and discussed at length. The structure of the text is intended to make
the treatment of each disorder accessible to even the most introductory reader.
I begin the discussion of each disorder with an examination of its epidemiol-
ogy and aetiology. The speech, language, hearing, voice and swallowing fea-
tures of these disorders receive extended discussion, which will be informative
even to advanced readers. Techniques and issues in the assessment and treat-
ment of communication and swallowing disorders are addressed in dedicated
sections. The recent emphasis in healthcare on evidence-based practice is never
far from sections on intervention with the results of efficacy studies presented,
when these are available.
It will be obvious from my comments thus far that I have had a diverse read-
ership in mind in my writing of this book. Clearly, my primary readership is
students, researchers and practitioners in speech and language therapy. As
anyone who has a professional or academic interest in speech-language pathol-
ogy will be aware, the field is a multidisciplinary one that draws on develop-
ments in and insights from medicine, linguistics, psychology and special
education, to name but a few areas. For this reason, I have tried to make the
reader aware of those multidisciplinary influences. For example, speech and
language therapists are actively involved in research projects that are examin-
ing the genetic bases of communication disorders and, accordingly, I examine
the findings of this research in the chapters that follow. Although speech and
language therapists form the primary readership of this book, they are by no
means the only readers who are likely to find the discussion in subsequent
chapters relevant to their fields of study and practice. Students of and practi-
tioners in medicine and nursing must understand the pathologies and injuries

that can lead to communication and swallowing disorders, as well as the pre-
sentation of these disorders. Educationalists encounter children in mainstream
and special education settings who have significant communication disorders.
A working knowledge of these disorders is thus an essential attribute of these
professionals. Social workers and psychologists work with children and adults
who have autistic spectrum disorders, mental health problems and learning dis-
abilities. The communication problems that attend these disorders are dis-
cussed at length in this book. Finally, parents and carers of children and adults
with communication and swallowing disorders rightly expect to be informed
about the causes, nature and likely course of these disorders. Many have
acquired a considerable level of expertise in the particular communication
impairments that affect their child or spouse. It is hoped that this book will con-
tribute to the knowledge base of these individuals as well.
PREFACE
xiv
1
The Scope of Clinical Linguistics
1.1 A New Definition of an Established Practice
In this book, I want to give new prominence to the somewhat neglected expres-
sion ‘clinical linguistics’. I say ‘expression’ rather than ‘field of study’ because,
of course, clinical linguistics has been a thriving area of enquiry amongst
researchers and practitioners in speech and language therapy for many years
now.
1
However, while the practice of clinical linguistics in academic and clin-
ical contexts has expanded considerably, the term ‘clinical linguistics’ has lost
out to competitor expressions, such as ‘clinical communication studies’.
Although the reasons for this shift towards these other expressions are clear
enough – for example, the need to have a broader term that can cover the full
range of disorders that are encountered by clinicians – I believe the term ‘clin-

ical linguistics’ gives due emphasis to the role of language in communication
and highlights the essentially scientific character of linguistics itself. In this
book, I adopt the following definition of clinical linguistics:
Clinical linguistics is the study of the numerous ways in which the
unique human capacity for language can be disordered. This includes
‘language disorders’, as standardly conceived. However, it also
includes disorders that result from disruption to the wider processes
of language transmission and reception and disorders of the vegetative
functions that are an evolutionary precursor to language. Most notably,
it includes all the disorders that are encountered by speech and lan-
guage therapists
2
across a range of clinical contexts.
This definition emphasises the fact that when we are studying clinical
linguistics, we are engaging not simply with an academic discipline, but also
1
with an area of clinical practice. By placing language at the centre of the above
definition, I am seeking to re-establish language as the foundation of all human
communication. Quite apart from being unrelated to language, speech, voice
and fluency disorders on this definition represent various types of breakdown
in the mechanics of language transmission. Indeed, it is their capacity to reduce
the effectiveness with which language meaning is transmitted that makes these
disorders distressing and frustrating for the individuals whom they affect. (To
see that this is the case, one need only think about the common complaints of
the severe stutterer, apraxic adult or dysarthric child: ‘People don’t understand
what I’m saying,’ ‘It’s a struggle to get across to people exactly what I mean,’
‘I have the words in my mind, but I just can’t get them out.’). We will return to
this issue at numerous points in the following chapters.
A further important dimension of the above definition – one that is fre-
quently overlooked in summaries of this clinical area – is the recognition that

language is largely dependent on earlier evolutionary developments in humans,
specifically those that have given rise to the neuromuscular mechanisms that
make feeding, swallowing and breathing possible. These vegetative functions
are frequently disordered as a result of trauma and disease. It will be seen in the
chapters to follow that the assessment and treatment of these functions, par-
ticularly swallowing, constitute a significant and growing aspect of the work of
speech and language therapy.
In conclusion, the above definition seeks to emphasise the place of practice
in clinical linguistics, to re-establish the foundational role of language in all
human communication and to recognise the important, but frequently over-
looked, work on feeding and swallowing disorders in speech and language
therapy. In its consideration of all three of these features, this definition moves
beyond previous accounts of clinical linguistics.
3
Yet, in doing so, it is not
entirely without precedent. An examination of recent issues of the journal
Clinical Linguistics and Phonetics reveals articles that address swallowing ability
after intra-oral cancer (emphasis on vegetative function), the education of
speech-language pathologists (emphasis on clinical practice) and a range of lan-
guage functions in disorders as diverse as stuttering, right hemisphere damage
and hearing impairment (emphasis on language). However, having completed
this initial examination of clinical linguistics, we are still some way off giving a
full account of the scope of its domain. In order to obtain such an account, we
must first consider the many different ways in which communication can be
disordered in humans.
1.2 Human Communication: Processes
The Royal College of Speech and Language Therapists estimates that 2.5
million people in the UK have a communication disorder.
4
Of this number,

THE SCOPE OF CLINICAL LINGUISTICS
2
some 800,000 people have a disorder that is so severe that it is hard for anyone
outside their immediate families to understand them. In this section, I begin
an examination of the wide range of communication impairments that make up
these large and significant figures. To begin with, however, a few words are in
order about the processes of normal communication.
Before we can utter a single word, we have to be capable of forming thoughts
that are appropriate for communication. The qualification ‘appropriate’ is
important in this context, as we all entertain thoughts that violate social and
moral codes and are rarely, if ever, communicated. Moreover, many other
thoughts are below the level of our conscious awareness and, as such, are not
communicated. In short, we each entertain many more thoughts than are ever
actually communicated. Those thoughts that are to be communicated give rise
to a communicative intention. Pragmaticists argue that it is only when a hearer
has established a speaker’s communicative intention in speaking that a speaker
can be said to have communicated anything at all.
5
In order that the hearer may
identify the speaker’s intention, the speaker must first encode it using a con-
ventional symbol system (one that is recognised and understood by other com-
municators) that can be readily transmitted. Language is such a symbol system.
Language encoding is a complex process that involves many interrelated stages.
These stages involve a combination of lexical, semantic, syntactic and phono-
logical processes. Their combined effect is to transform an abstract, nonlin-
guistic intention into a still abstract, but now linguistic representation. This
representation is still not of a form where it can be uttered by a speaker. Various
neuromuscular selections must be made during motor programming, before
the speaker is finally able to translate these selections into movements of the
articulators during speech production (a stage called motor execution).

Thus far, we have outlined the four main processes of communication that
are essential to the production (expression) of an utterance. To recap, these
processes are: (1) thought genesis, (2) language encoding, (3) motor program-
ming and (4) motor execution. However, even if a communicator is able to fulfil
the requirements of these processes, he or she still has not communicated any-
thing at all. As we discussed above, communication can only be said to occur
when a hearer is able to retrieve the intention that motivated the speaker’s
utterance. Our four productive processes must now be matched to four recep-
tive processes, the combined function of which will be to determine this inten-
tion on the basis of an input linguistic utterance. In the first of these receptive
processes – sensory processing – sound waves are converted into mechanical
vibrations via the actions of the tympanic membrane (ear drum) and ossicles.
These vibrations trigger a series of neurochemical reactions within the cochlea
of the inner ear. From here, nerve impulses make their way along auditory
nerves to the auditory cortices of the brain. These cortices, both of which are
located in the temporal lobes, are integral to our second main receptive process,
HUMAN COMMUNICATION: PROCESSES
3
speech perception. Although the exact mechanism by means of which hearers
perceive speech sounds is still uncertain, it seems clear that top-down processes
and contextual influences play a significant role (Massaro 2001). Speech per-
ception is vital to the eventual recovery of a speaker’s communicative inten-
tion.
6
However, it is by no means the only form of perception that plays a role
in this process. One need only consider how often visual information serves to
disambiguate a speaker’s utterance to appreciate the significance of visual per-
ception in this process too. Before complete disambiguation can occur, the
product of perception must undergo a third receptive process, language decod-
ing. In decoding, structural (syntactic) relations within sentences are deter-

mined alongside the semantic features of constituent lexemes. Decoding
arrives at a propositional meaning of the sentence which is not yet the full
intended meaning of the speaker’s utterance. This latter meaning can only be
obtained by establishing the speaker’s communicative intention in producing
the utterance, a process that leads us back to the domain of thoughts. It can be
seen that in an effort to describe communication between a speaker and a
hearer, we have effectively come full circle, a fact that is aptly demonstrated by
Figure 1.1.
1.3 Human Communication: Disorders
The communication model that I outlined in the previous section is limited in
a number of ways. It assumes an oral-auditory mode of communication when,
in fact, other modes of communication are possible (e.g. written-visual com-
munication). At every point in this model, I make claims about communication
which appear to be unproblematic, but which are, in reality, deeply contentious
THE SCOPE OF CLINICAL LINGUISTICS
4
S
p
e
a
k
e
r
H
e
a
r
e
r
Communicative

intentions
Language
encoding
Language
decoding
Speech
perception
Sensory
processing
Speech
Motor
execution
Motor
programming
Figure 1.1: The process of communication
(e.g. claims about speech perception, which depend on the psychological
reality of the phoneme
7
). The model makes no mention of the role of context
in communication and is almost entirely ‘mentalistic’ in character. But as every
student of communication knows, context pervades communication – from
deciding what thoughts it is appropriate to express in a certain situation (social
context) to speaking more loudly than normal in a busy train station (physical
context), it is inconceivable that any form of communication could proceed in
the absence of context. However, despite these drawbacks – and no doubt
others besides – the above model can be used to demonstrate the loci of com-
munication breakdown and the disorders that result when such a breakdown
occurs. In this section, I present an overview of these disorders and indicate to
the reader something of their treatment in subsequent chapters.
Many communication disorders have their origin at the level of thoughts

and, specifically, in an inability to formulate appropriate intentions for com-
munication. These disorders have a diverse aetiology which includes psychotic
conditions like schizophrenia, mental retardation (as occurs, for example,
in Down’s syndrome) and the early-onset condition of autism. Individuals
with advanced dementia lack all communicative intent and are essentially
mute. Although Alzheimer’s disease is the most common cause of dementia,
other causes include human immunodeficiency virus (HIV) infection and
Creutzfeldt-Jakob disease (CJD). These conditions and their associated com-
munication disorders present numerous management challenges not just for
speech and language therapists, but for other healthcare professionals and
carers as well. They will be discussed at various points in subsequent chapters,
but primarily in chapters 3 and 5.
Disorders of language encoding and decoding are frequently encountered
by both paediatric and adult clinicians. These disorders include aphasia in
adults (known as ‘acquired aphasia’). Aphasia has been the focus of extensive
research and classification for some years. Its linguistic characteristics and
impact on communication will be examined in detail in chapter 5. Childhood
(‘developmental’) language disorders are no less diverse than their adult coun-
terparts. These include cases of phonological disorder, children with specific
language impairment who present with morphosyntactic deficits and children
for whom the pragmatics of language poses considerable barriers to effective
communication. These latter children have been variously described as having
semantic-pragmatic disorder (Bishop and Rosenbloom 1987) or semantic-
pragmatic deficit syndrome (Rapin and Allen 1983), although the validity of
this diagnostic category is now strongly disputed in some quarters (Gagnon
et al. 1997). In chapter 4, we examine these common language disorders in
children. We will also discuss other, not so common language disorders in chil-
dren, such as Landau–Kleffner syndrome (also known as acquired epileptic
aphasia).
HUMAN COMMUNICATION: DISORDERS

5
In chapters 4 and 5, we examine the motor programming disorder, apraxia.
This disorder can affect a range of volitional movements, although automatic
movements are unaffected. When the disorder involves movements that are
necessary for speech production, the resulting condition is called verbal apraxia
or apraxia of speech. (Contrast with limb apraxia, when movements of the arms
and legs are compromised.) The disorder has both developmental and acquired
forms and can occur in isolation or in conjunction with other communication
impairments (e.g. phonological disorder). When the latter situation pertains, a
differential diagnosis is both necessary and difficult. In chapter 4, we examine
the criteria that guide such a diagnosis. A large number of disorders can disrupt
the motor execution of speech. Neurological damage can cause dysarthria, in
which impoverished movements of the articulators give rise to varying levels
of unintelligibility. The same nerves and muscles that are impaired in
dysarthria can also cause disorders of feeding and swallowing (dysphagia), as
well as problems such as drooling. Even when nerve and muscle function is
normal, the structure and function of the articulators can be compromised
through disease and subsequent surgery (e.g. glossectomy) or as a result of
defective embryological development (e.g. cleft lip and palate). Benign and
malignant lesions of the tissues of the larynx, particularly the vocal folds
(cords), can produce disorders of voice; similar lesions in the nasal cavities (e.g.
nasal polyps) or dysfunction of the velopharyngeal port (velopharyngeal
incompetence) distort normal resonance. Finally, speech production can be
severely disrupted in stuttering (stammering). Although the exact causal
mechanism at work in this disorder of fluency is unknown, it is unlikely to be
simply an organic aetiology, such as occurs in many other motor execution dis-
orders. Cleft lip and palate, fluency disorders and voice disorders will be exam-
ined in detail in chapters 2, 6 and 7, respectively. Developmental and acquired
dysarthria will be discussed in chapters 4 and 5.
Sensory processing disorders both cause and contribute to communication

breakdown in a number of ways. The most obvious way is through complete or
partial loss of hearing. At various points in the following chapters, we examine
conductive and sensorineural deafness and describe the different forms of
audiometry that are used to assess and diagnose hearing disorders. We consider
the role of the speech and language therapist in the clinical audiology team.
Hearing disorders are not the only sensory processing problems of concern to
the speech and language practitioner. Reduced sensation in the oral cavity can
result from cranial nerve damage, which may be caused by a cerebrovascular
accident (CVA). These and other sensory impairments exacerbate existing com-
munication and swallowing problems and pose a considerable treatment chal-
lenge to clinicians. Finally, some individuals who have intact sensory receptors
(i.e. normal hearing, vision, etc.) can nonetheless struggle to recognise the
sensory information that is the output of those receptors. This disorder, called
THE SCOPE OF CLINICAL LINGUISTICS
6
agnosia, can affect one or more sensory modalities, resulting in auditory agnosia,
visual agnosia and so on. Due to their common neurological aetiologies, agnosia
is often found alongside disorders like aphasia. For this reason, it will be exam-
ined in chapter 5. However, we will have occasion to discuss agnosia, particu-
larly auditory agnosia, in other contexts as well – for example, in chapter 4, when
we will examine auditory agnosia in Landau–Kleffner syndrome.
Communication processes and disorders are shown in Table 1.1.
1.4 The Contribution of Linguistic Science
In the previous section, we described a number of disorders of receptive and
expressive language. In order to characterise these disorders, we must draw
upon the terminology of different branches of linguistic science. Language
can be impaired in any one – and usually it is impaired in more than one – of
the following areas: phonetics, phonology, graphology, morphology, syntax,
lexicology, semantics and pragmatics. In this section, I describe these linguis-
tic areas and examine the types of deficit that result when these areas are

disordered.
THE CONTRIBUTION OF LINGUISTIC SCIENCE
7
Table 1.1 Communication processes and disorders
Communication processes Communication disorders
Communicative intentions Problems formulating and establishing communicative
intentions. Associated with psychotic disorders (e.g.
schizophrenia), mental retardation (e.g. Down’s
syndrome), autism and dementia (e.g. Alzheimer’s
disease)
Language encoding and decoding Problems formulating and understanding various levels of
language. Disorders include acquired aphasia and
phonological disorder, specific language impairment and
pragmatic language impairment in children. Also includes
a rare disorder in children, Landau-Kleffner syndrome
Motor programming Apraxia (developmental and acquired)
Motor execution Disorders of speech production. Includes dysarthria
(developmental and acquired), disorders related to
articulation (e.g. cleft lip and palate), phonation (e.g. vocal
nodules), resonation (e.g. velopharyngeal incompetence)
and fluency (e.g. stuttering). Also includes related
disorders of swallowing (dysphagia) and drooling
Sensory processing Hearing disorders (e.g. conductive and sensorineural
deafness) and oral sensory dysfunction
Perception Agnosia. Affects different sensory modalities, resulting in
auditory agnosia, visual agnosia, etc.
Phonetics is the study of speech sounds. This includes the study of the
articu latory movements that are required to produce speech sounds (articula-
tory phonetics) and the measurement of the physical dimensions of speech
sounds, such as amplitude and frequency (acoustic phonetics). By contrast,

phonology is the study of the sound system of a language. Phonologists
examine how speech sounds function to signify meaning: for example, how the
difference of one distinctive feature (voice) between ‘pin’ /
pn/ and ‘bin’ /bn/
conveys two unrelated meanings. This symbolic dimension of phonology – and
the lack of such a dimension to phonetics – is the basis of the long-standing
clinical distinction between speech and language disorders. In this way, the
dysarthric adult, who cannot perform the articulatory movements that are
required in order to produce speech sounds, has a speech disorder. The young
child, who cannot signal a difference in meaning between ‘sip’ and ‘zip’ (both
of which are pronounced [
sp]), has a phonological (language) disorder. Speech
(phonetic) and language (phonological) disorders often coexist; indeed, a
speech disorder may contribute to the development of a phonological disorder.
For example, the child with a cleft palate may present with severe velopharyn-
geal incompetence. This inability to achieve full velopharyngeal closure makes
it difficult or impossible for the child to articulate oral plosives (the resulting
productions are heavily nasalised). The child may substitute all oral plosives
with glottal stops, as the glottis is the only point in the vocal tract where the
requisite build-up of air pressure can be achieved. No longer able to produce
the sound contrasts that would enable a listener to distinguish ‘pin’ /
pn/ from
‘kin’ /
kn/, or ‘bin’ /bn/ from ‘din’ /dn/ – all of which are realised as [ʔ˜n]–
this child has a phonological disorder. To the extent that this disorder has its
origin in a failure of normal velopharyngeal valving (a speech defect), a phono-
logical and a phonetic disorder are intimately connected in this case.
Graphology is the study of the system of symbols that is used to communi-
cate a language in its written form. Written language has seldom received the
extensive treatment that is given to spoken language in books on linguistics in

general and on clinical linguistics in particular. Speech and language therapy
courses include as routine modules on phonology and phonological disorders.
(Phonology is the spoken language counterpart of graphology.) However, these
same courses do little more than mention graphology, while disorders of
graphology are only briefly addressed, usually in relation to conditions like
aphasia. To some extent, this more limited treatment of written language is
merely a reflection of the fact that speech is our primary mode of linguistic
communication. It is also indicative, however, of the lack of clinical research
that has been conducted into written language processes and disorders. Two
disorders of written language are acquired dyslexia and acquired dysgraphia.
As the term ‘acquired’ suggests, these disorders occur in individuals who have
intact written language skills prior to the onset of a CVA or other neurological
THE SCOPE OF CLINICAL LINGUISTICS
8
event (e.g. traumatic brain injury). Dyslexia and dysgraphia also occur as devel-
opmental disorders in children. Given the educational implications of
these disorders, they are assessed by educational psychologists and managed by
specialist teachers. In their acquired forms, dyslexia and dysgraphia usually
exist as part of the central language disorder aphasia. However, even when lan-
guage is intact, a client may struggle to produce and perceive the letters
(graphs) that are used in writing. On some occasions, this is the result of a visual
impairment. On other occasions, the client has normal vision, but is unable to
recognise letters. On still other occasions, a client is unable to write letters on
account of weakness or paralysis of the arm and hand. (This is commonly seen,
for example, in right-sided hemiplegia following a left-hemisphere CVA.)
In these cases, the disorder is the result of deficits, respectively, in the sensory
processing, visual perception and motor execution of the written symbols of
language.
For most linguists, grammar consists of two main areas of study: morphol-
ogy and syntax. Morphology is the study of the internal structure of words.

This structure may be simple and consist of a single morpheme. Such
monomorphemic words include ‘neighbour’ and ‘crocodile’. (The reader will
note that monomorphemic is not the same as monosyllabic.) It is frequently the
case, however, that words consist of two or more morphemes. These polymor-
phemic words – examples include ‘cats’ and ‘navigator’ – contain bound and
free morphemes. A free morpheme can stand independently of other mor-
phemes as a word of the language. (In the example ‘cats’, cat is a free mor-
pheme.) Bound morphemes, as their name suggests, have no independent
existence as words of the language. (In the example -s and -or are bound mor-
phemes.) These morphemes can inflect to express grammatical contrasts. The
-s suffix of ‘cats’ is an inflectional morpheme, as it signals a grammatical dis-
tinction between singular and plural. Other bound morphemes are involved in
the construction of new words and do not express grammatical contrasts. The
-or suffix of ‘navigator’ is such a derivational morpheme.
In chapter 4, we review the findings of studies that have investigated inflec-
tional morphology and other aspects of grammatical morphology (e.g. use of
pronouns) in children with specific language impairment (SLI). In general,
these studies have revealed that SLI children use significantly fewer inflectional
and grammatical morphemes and use significantly more incorrect inflectional
and grammatical morphemes than MLU controls (controls matched to SLI
subjects on mean length of utterance). Morphemic deficits are also evident in
other clinical populations. In chapter 5, we examine a number of these deficits
in the language of schizophrenic speakers.
Syntax is the study of the internal structure of sentences. At its most basic,
this structure consists of words that are nouns (‘man’), verbs (‘sing’), adjectives
(‘blue’), adverbs (‘quickly’), prepositions (‘beside’), articles (‘the’) and so on.
THE CONTRIBUTION OF LINGUISTIC SCIENCE
9
These words come together to form phrases, some of which exhibit extensive
pre- and postmodification. For example, the patient and the difficult patient in

the waiting room are both noun phrases. However, the complexity of the second
noun phrase derives from the presence of a premodifying adjective (‘difficult’)
and a postmodifying prepositional phrase (‘in the waiting room’). Phrases
combine to form sentences or clauses within sentences. The combination of the
noun phrase the man and the verb phrase walks in the park results in the simple
sentence The man walks in the park. However, this latter construction may exist
as a clause within a larger sentence (Although the man walks in the park, he is still
very overweight), the parts of which are linked by a conjunction (in this case,
the subordinating conjunction ‘although’).
There are many children and adults for whom the above syntactic levels pose
considerable difficulties. Phrase structure is effectively absent in the autistic
child who produces only single-word utterances. (More often than not, even
single-word utterances are absent.) The agrammatic aphasic omits function
words (e.g. articles) and inflectional morphemes. These omissions generate an
incomplete, simplified phrase structure that is telegrammatic in appearance
(hence, the use of the term ‘agrammatism’ to describe this type of aphasia).
Many clients who fail to produce adequate phrase structure may also be unable
to comprehend phrases such as ‘the tall man’ and ‘on the table’. Receptive
problems at the level of phrase structure are often most apparent during formal
testing, when the client is unable to use contextual cues to facilitate compre-
hension. Clauses and sentences are often severely compromised in the schizo-
phrenic patient. In addition to impairments at each of these syntactic levels, the
language-disordered client may fail to invert subject pronouns and auxiliary
verbs (such as occurs, for example, in the asking of questions), may fail to form
the negatives of verbs and may be unable to decode the structural relation
between subject and object nouns in a passive sentence. We will examine these
syntactic deficits, and many others besides, in the following chapters.
Lexicology is the study of the vocabulary of a language. Like graphology
before it, lexicology has been largely overlooked by clinical linguists. This
neglect is understandable in part; by and large, academic linguists have tended

to pursue historical treatments of lexicology, which are of limited relevance to
the clinician who must assess and treat language and communication disorders.
Yet, there are clear reasons why greater integration of lexicology with clinical
linguistics should be encouraged. First, through studies of vocabulary devel-
opment in children, we have gained considerable insight, not simply into lan-
guage learning, but also into cognitive developmental processes more generally.
The potential exists to expand our knowledge of these processes further.
However, that potential will only be realised by embracing the expertise of dis-
ciplines like lexicology more fully. Second, for some time studies have indicated
that early vocabulary development is a reasonably strong predictor both of the
THE SCOPE OF CLINICAL LINGUISTICS
10