articulation characteristics of severely and profoundly deaf children and approaches to therapy: a...

Articulation Characteristics of Severely and ProfoundlyDeaf Children and Approaches to Therapy: A Review ofthe Electropalatography Literature

Lucy Ellis*University College Plymouth

Abstract

This article provides a concise review of (i) the segmental articulation errors produced by severelyand profoundly deaf children and (ii) the approaches to therapy carried out to remediate theseerrors. In both cases, evidence is gathered from studies using electropalatography (EPG), an instru-mental technique which provides a direct articulatory display of the timing and location of contactbetween the tongue and the hard palate during speech. Attention is paid to what is known aboutthe generalisation and maintenance of improvements in speech production following EPG visualfeedback therapy.

Introduction

Speech and hearing scientists are in general agreement that speech movements areplanned to achieve sequences of auditory goals (McGarr and Harris 1983; Perkell et al.2000; Vick et al. 2001). In hearing speakers, close mappings between production and per-ception mechanisms are acquired at an early age and then maintained through the use ofauditory feedback. The speech of deaf children tends to differ from normal speechbecause of the different sensory conditions under which it must be learnt, namely absentor partial auditory feedback. It should be emphasised here that these issues are relevantonly for those individuals and their families who have chosen the oral ⁄ aural route tocommunication, either in combination with signing or in exclusion. The use of the term‘deaf’ in this review is intended to cover the whole range of hearing impairment,although the focus of the discussion is the speech of severely and profoundly deaf speak-ers. Where the term ‘hearing impaired’ is used, this reflects the terminology used by theauthors of the research being reviewed.

In terms of the effect of loss of hearing on speech production, the phonatory, oro-nasaland articulatory speech production processes can be affected, giving rise to errors detect-able at the level of individual speech sounds (segmental level) and at the level detected asrhythm, intonation, stress and speech rate (suprasegmental level). There is a large variationamongst speakers with regard to the extent of impairment across these domains. To com-pensate for lack of auditory feedback, deaf speakers tend to rely on somato-sensory feed-back for information on how to coordinate articulatory movements. An over-reliance onthis may lead to over-produced or effortful speech. In terms of the effect on individualspeech sounds, difficulties are experienced for both consonants and vowels. Intelligibilityof speech is, in fact, well correlated with percentage of segmental errors, both consonantaland vocalic (Hudgins and Numbers 1942; Monsen 1983; Maasen and Povel 1985;Fletcher et al. 1991). One hypothesis is that deaf speakers place the articulators fairly

Language and Linguistics Compass 3/5 (2009): 1201–1210, 10.1111/j.1749-818x.2009.00151.x

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accurately, especially the highly visible sounds, but fail to coordinate the movements ofthe total of the articulators. This leads to the claim that many errors are the consequencesof incorrect motor planning in time (Vick et al. 2001).

A noticeable acoustic fact about the speech of deaf individuals is the instability ofvowel production. Some researchers claim that deaf speakers move their articulatorsthrough a relatively restricted spatial range within the oral tract with the effect of neutral-ising the contrasts between vowels (McGarr and Harris 1983; Nicolaidis and Sfakianaki2006). Instability of speech in deaf individuals and the deleterious consequence for intelli-gibility is amply demonstrated in the research literature. This review will concentrate onerror patterns amongst those with a severe-to-profound hearing loss in the articulatorydomain, specifically, those relating to consonants.

The Technique of Electropalatography

Electropalatography (EPG) is a technique which reveals contact patterns over timebetween the tongue and the hard palate during speech. Over the last 40 years or so, thetechnique (also known as dynamic palatography) has developed to become established asan effective research and therapy tool. EPG requires the speaker to wear an artificial pal-ate which is similar to an orthodontic brace and fits against the hard palate. The palatehas silver electrodes embedded in it and when the tongue touches these electrodes thepattern can either be viewed immediately, as appropriate for visual feedback during ther-apy or analysed later using specialised software. There are a number of systems availablewhich differ in software for analysis and treatment (see Stone 1997; for a review). For areport on the latest developments of the technique by Articulate Instruments Ltd and itsclinical applications, see Scobbie et al. 2004.

The major contribution of EPG is that it demonstrates objectively the detail and sub-tlety of articulation and can detect important lingual behaviours, which were not identi-fied by perceptual analysis (transcription) alone. In the case of pathological speech, thetechnique can reveal the underlying phonology and therefore enables the evolution andrevision of theoretical frameworks (e.g. Scobbie et al. 2000). The production of differentspeech sounds that involve tongue–palate contact generates different EPG patterns. EPGrecords contact patterns for approximately three-quarters of the total range of consonantsin English and it also provides information about production of some vowels. Whilethere will be individual differences in the detail of tongue–palate contact patterns pro-duced during speech, characteristic patterns are produced by normal speakers for soundssuch as ⁄ t ⁄ , ⁄d ⁄ , ⁄n ⁄ , ⁄k ⁄ , ⁄g ⁄ , ⁄ s ⁄ , ⁄ z ⁄ , ⁄ l ⁄ , ⁄ sh ⁄ (as in shop), ⁄ ch ⁄ (as in chop), ⁄ j ⁄ (as inyou) and ⁄ng ⁄ (as in sing). Figure 1 shows typical tongue–palate contact patterns for the

Alveolar stops: t, d and n Velar stops: k, g and ng

Fig. 1. Characteristic tongue–palate contact patterns produced by normal speakers for alveolar stops ⁄ t ⁄ , ⁄ d ⁄ and⁄ n ⁄ (left-hand panel) and velar stops ⁄ k ⁄ , ⁄ g ⁄ and ⁄ ng ⁄ (right-hand panel).

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ª 2009 The Author Language and Linguistics Compass 3/5 (2009): 1201–1210, 10.1111/j.1749-818x.2009.00151.xJournal Compilation ª 2009 Blackwell Publishing Ltd

alveolar stops ⁄ t ⁄ , ⁄d ⁄ and ⁄n ⁄ and for the velar stops ⁄ k ⁄ , ⁄g ⁄ and ⁄ng ⁄ . For the alveolarstop pattern, major contact occurs across the alveolar region, behind the front teeth andalong the sides of the hard palate. For the velar stop pattern, contact appears at the backof the palate in the velar region.

It is an effective tool for the phonetically realistic characterisation of disordered speechfor diagnosis and provides visual feedback therapy for treatment of speech disorders aris-ing from a variety of aetiologies. The clinical potential of the technique has beendescribed in a wide range of case studies (for a review, see Hardcastle and Gibbon 1997and for a comprehensive annotated bibliography, see Gibbon 2006). It is a technique forresearch into the motor control mechanism that underlies normal speech (e.g. Fougeronand Keating 1996; Ellis and Hardcastle 2002; Dixit and Hoffman 2004) and disorderedspeech (e.g. Hardcastle and Gibbon 1997; Bernhardt et al. 2003; Pantelemidou et al.2003; Gibbon et al. 2004).

Articulation Errors in Deaf Speech Described by EPG

Most of what is known about the spatio-temporal detail of articulation errors in deafspeakers is drawn from a small but coherent literature on the description, diagnosis andremediation of articulation errors using EPG in individuals or in small groups of deafspeakers. In the aforementioned EPG bibliography (Gibbon 2006), there are currently 16papers that address the speech difficulties of this clinical population. Most of these reportclinical case studies and the majority of the research addresses the speech of children.

A number of factors are known to influence the development of speech in deaf indi-viduals. These include factors associated with the individual, for example, the aetiologyand degree of hearing loss, extent of motivation to communicate orally and related abili-ties such as linguistic, motor, perceptual and cognitive. Intervention factors also play apart, for example, age of detection, amount and frequency of intervention and treatmentrationale. In addition to these multifarious influences, it is generally agreed that it is hardto find a stereotypical performance in severely and profoundly deaf speakers and that thisis in part because of the acknowledged variability in segmental production between andwithin speakers compared with speakers with normal hearing (for EPG evidence of thissee Dagenais and Critz-Crosby 1991). Nevertheless, the qualitative error types for conso-nants most frequently discussed in the literature are omissions, distortions, substitutionsand voicing errors. Classification of errors into these categories has frequently been basedon impressionistic transcription data. EPG studies have provided similar findings and theseand additional insights are discussed hereunder. The discussion is not intended to beexhaustive, but will highlight those most common findings.

Omission of consonants is the most frequently found error, especially for velar soundssuch as ⁄k, g ⁄ and ⁄ng ⁄ and for consonants in word-final position. Bernhardt et al. (2000:12)comment that omission often occurs in sounds in word positions of lower intensity andpitch such as word-final position, consonant clusters and weak (unstressed) syllables.

Distortions of consonant production are also more frequent in word positions withlower intensity and pitch. Consonants are typically long in duration and consonant clus-ters are particularly problematic (e.g. splash). Crawford (1995) in an EPG study of twoprofoundly deaf children being trained to produce velar stops used the label ‘distortion’to describe pre-therapy target velars ⁄k and g ⁄ which show simultaneous contact in thealveolar and velar region of the palate.

Substitutions are also commonly found and usually take place at word-initial position.Typically, stops are produced for other sound classes, with fricatives most often replaced.

1203 Articulation Characteristics of Severely and Profoundly Deaf Children


As a subclass of speech sounds, sibilant fricatives ⁄ s, z and sh ⁄ have been shown by EPGdata to be the least correctly produced consonants (Dagenais and Critz-Crosby 1991).Substitution errors also involve the production of glottal stops, which can occur in placeof many sounds. Many observers have commented on the predominance of consonants ata front place of articulation, particularly labials. This is partly brought about by the factthat interdentals (such as ⁄ th ⁄ and its voiced counterpart ⁄dh ⁄ , as in those) and dentals(such as ⁄ f, v ⁄ ) can be fronted to a bilabial place of articulation. It is thought that labialsoccur often because their production can be easily viewed by the listener in face-to-faceconversation, unlike most other consonants the production of which is hidden within theoral tract. Finally, voicing errors are also noted and usually occur for stops and fricatives.Typically, voicing contrasts are not sufficient for perceptual differentiation between pairsof stops, for example ⁄ t ⁄ versus ⁄d ⁄ or ⁄p ⁄ versus ⁄b ⁄ or between pairs of fricatives suchas ⁄ f ⁄ versus ⁄v ⁄ or ⁄ s ⁄ versus ⁄ z ⁄ .

An issue highlighted in an EPG study of 18 unintelligible profoundly deaf children, byDagenais and Critz-Crosby (1991) concerns a prevalence of what they refer to as an‘open gesture’. This gesture was identified most frequently for target sounds ⁄ t, d, k, g, s,z ⁄ but not target ⁄ sh ⁄ . It is one of four categories of gesture they have defined usingEPG which shows either no tongue–palate contact at all or no more than two contactsper side. The other categories are, ‘closed contact’ (a broad area of undifferentiated con-tact across the palate), ‘front occlusion’ (similar to a typical alveolar stop produced by ahearing speaker), ‘back occlusion’ (similar to a typical velar stop produced by a hearingspeaker) and ‘presence of a groove’ (similar to that used for typical ⁄ s, z ⁄ or ⁄ sh ⁄ ). Theauthors do not offer a discussion on how the open gesture maps onto the traditional errortypes for deaf speakers of omission, substitution or distortion. However, instrumentalidentification of open gestures corresponded to listener identifications across the wholerange of possible responses for consonant targets.

Approaches to Therapy: Conventional Intervention

For deaf children who choose spoken English as their primary mode of communication,support for the development of intelligible speech increases the likelihood of social andemotional well-being and educational and employment opportunities (Department forEducation & Skills 2005). Effective oral communication leads to better social interactionpossibilities, especially in terms of self-esteem and self-confidence amongst peers (Conti-Ramsden and Botting 2004). Integration into mainstream education and access to thecurriculum is more likely through an individual’s development of literacy skills as a resultof a more accurate and consistent phonological system (Hanson 1991).

The speech of severely and profoundly deaf children is known to be especially chal-lenging to assess and treat. It is a heterogeneous clinical population and generally speak-ing, speech and language therapists face the challenge of treating multiple errors of acomplex nature. For reasons of the severity of the hearing loss, disordered patterns aredifficult to change and therapists often refer to plateaus in progress. Intervention for allspeech disorders is based on phonetic transcription, a highly valued, specialised clinicaltool taking many years to develop, based on careful watching of and listening to a child’soral output. Despite well-documented limitations, ‘auditory-articulatory descriptionsremain the lingua franca of the speech and language therapy profession’ (Grunwell1993:2). However, these efforts are subjective leading to transcriptions containing intra-and inter-transcriber variability. The human perceptual system is not capable of detectingsome of the very subtle but potentially important distinctions found in disordered child

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speech (Scobbie et al. 2000, 2004). Amorosa et al. (1985:281) highlighted how ‘agree-ment [between transcribers] often did not reflect the child’s production, but rather thetranscribers’ ‘‘normalisation’’ of what they had heard’.

In terms of treatment, conventional therapy focuses on creating awareness in the childof tactile feedback during speech production and on maximising the utilisation of it toimprove articulatory accuracy. For instance, some children under-use their tongues forspeech and so effort is directed at increasing tongue displacement and active differentia-tion of parts of the tongue which is necessary for an auditory percept of categorically dif-ferent sounds. Many errors are due to incorrect tongue positioning and verbaldescriptions or line diagrams are used to try to change these speech behaviours.

Approaches to Therapy: EPG Intervention

To date, EPG has been applied in a limited way to speech problems experienced byseverely and profoundly deaf children. However, it has often proved to be highlymotivating for children. Fletcher et al. (1991:929) is typical in reporting results thatindicate that ‘visual articulatory modelling and feedback of linguapalatal contact patterns isan effective means of teaching consonants and improving speech intelligibility’. Pantelem-idou et al. (2003) speculate further on the mechanism of EPG’s efficacy: ‘By imitatingthe prescribed patterns of contact on the EPG display screen, a child who is deaf maybe encouraged to use tactile and proprioceptive sensory feedback information asassociative learning stimuli, substituting it for the auditory speech stimuli used by hearingchildren’.

The literature on EPG treatment with deaf children demonstrates significant positivechanges towards normal lingual-palatal contact patterns and improved intelligibility oftenfollowing several years of conventional therapy with little progress (Fletcher et al. 1980;Fletcher et al. 1991; Dagenais 1992; Crawford 1995; Parsloe 1998; Bernhardt et al. 2000;Derry and Bernhardt 2000). Similar results have been reported where EPG has been usedwith speakers with a cochlear implant (Bernhardt et al. 2000, 2003; Pantelemidou et al.2003). A majority of studies are of single cases or small groups, mostly reporting on thetherapy stage only which precludes observation of longer-term maintenance effects. Interms of EPG treatment duration, the shortest varied between 1 and 4 months and thelongest was 1 year in duration. Treatment was mostly delivered either once a week or, asin fewer studies, twice a week. Most of the EPG studies have targeted the same type ofconsonant errors and there is a broad similarity in treatment effects. Some of the differentapproaches taken and some of the more interesting issues are summarised below.

Fletcher et al. (1991) is typical in reporting significant improvements in both EPG con-tact patterns and listener perceptions in the place and manner of consonants in all the deafchildren they studied. Dagenais et al. (1994) found that as the learning of more typicallingapalatal contact patterns increased, intelligibility increased. Perceptual scores for pro-foundly deaf participants were consistently higher subsequent to visual feedback therapycompared with the scores subsequent to traditional therapy. This finding appears to be insympathy with the received expectation that ‘dynamic lingualpalatal contact information,combined with clinician observations, would...foster systematic, unambiguous progresstoward intelligible speech (Fletcher et al. 1980; Fletcher & Hasegawa, 1983). At present,there has been no large scale study to provide evidence of systematic progress and asregards what form this would take.

Some studies focused on gaining a particular phonological contrast such as ⁄d ⁄versus ⁄g ⁄ or ⁄ s ⁄ versus ⁄ sh ⁄ (Fletcher et al. 1991; Parsloe 1998). Parsloe (1998) showed



the development of a better articulatory and perceptual distinction (on the part of theparticipant) between ⁄ s ⁄ and ⁄ sh ⁄ following EPG visual feedback therapy. Parsloe(1998:119) discusses the idea that more accurate production can lead to sharper percep-tion and that ‘targets for production work are unlikely to be fully generalised by deafspeakers, unless those targets become within their listening range’. Some studies focus ontreating a wide range of sounds considered pathological (Dagenais 1992; Bernhardt et al.2000, 2003). Particular gains were achieved for sounds that were introduced using visualfeedback having previously been absent from speech (Fletcher et al. 1991; Dagenais 1992;Crawford 1995; Pantelemidou et al. 2003; Bernhardt et al. 2003). Bernhardt et al.(2003:214) reported that the four adolescents with moderate-to-severe hearing loss theytreated showed the greatest gains in their speech for consonants that were absent or mar-ginal in their speech before treatment. Specifically, these were ⁄ s, z, sh ⁄ and ⁄ l, r ⁄ . Theauthors comment that ‘visual feedback may be most useful in facilitating the establishmentof new articulatory patterns’. Dagenais and Critz-Crosby (1991:1434) found that theirdeaf speakers who had ‘near-correct productions before training had greater difficulty cor-recting these productions than did speakers who initially had more unique, undifferenti-ated productions’. They suggest that this was the case because they had to ‘unlearn’ oldpatterns before new ones could begin.

Generalisation and Maintenance of Treatment Effects

For any speech therapy intervention, the generalisation and maintenance of newlyacquired speech skills, namely the achievement of functionally useful speech, are of pri-mary clinical interest. As with any behaviour-based therapy, the extent to which newhabits are adopted across related behaviour and time is a measure of efficacy of interven-tion. Generalisation refers to the ‘spontaneous’ resolution of speech deficits in targetedsounds to the same sounds in other phonetic contexts or syllable positions and to otherspeech styles such as connected or conversational speech. Applied to the use of visualfeedback therapy for disordered speech, maintenance refers to the continuation, or not,of improved articulation following either discharge or a resumption of standard (i.e. non-EPG) therapy. In a recent survey of 10 years of EPG therapy across a range of speech dis-orders in Scotland, Gibbon and Paterson (2006) report that a majority of 75 patientsexperienced some difficulties generalising skills into conversational speech. Specifically, of51 children who received EPG therapy, a minority (20%) were discharged at the end oftherapy because their speech difficulties had resolved completely. The remaining 80%continued to need carry-over speech therapy using approaches other than EPG’. Gibbonand Paterson 2006:288 acknowledge the salience of this issue by concluding that ‘theirsurvey has highlighted the need for future research into EPG therapy to measure general-isation and maintenance phases of therapy’.

All 11 EPG clinical studies of deaf speakers consider generalisation and ⁄or maintenanceto be important enough to report on and discuss their findings in varying amounts ofdetail and interest. With regard to generalisation, there are cases of successful transfer oftreated targets into untreated targets and spontaneous speech (Parsloe 1998; Bernhardtet al. 2000; Pantelemidou et al. 2003; Martin et al. 2007) and cases of no generalisationof treated targets into spontaneous speech (Crawford 1995). There is currently an absenceof clarity and focus on generalisation and maintenance processes in this clinical popula-tion. This is surprising given the importance that clinicians place on these aspects of ther-apy as a measure of success. If anything, generalisation and maintenance are even moreimportant to consider in light of the poorly understood learning process that is underway

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when visual feedback is ‘mapped into’ the processing space that the hearing loss has left.Informal consultation with local practitioners reveals that generalisation can be more lim-ited and can take longer in deaf children.

Bernhardt and colleagues (Bernhardt et al. 2000, 2003) provide a rare clear account ofgeneralisation not only across different speech styles but also within the phonetic andphonological structure of English, that is, ‘within sound classes, across voicing cognates,from one type of cluster to another, and across word positions’ (2000:32). They foundevidence of untreated targets that were phonetically similar to the treated targets showingsome influence of training through generalisation (treatment for ⁄ s ⁄ generalised as lessdentalisation on alveolar stops) and yet no transfer from ⁄ sh ⁄ to other phonetically similarsounds. The authors outline a useful paradigm for the monitoring of production changesin all sounds visible with EPG by differentiating (i) treatment targets, (ii) generalisationtargets and (iii) non-treatment control targets: ‘Significant gains for treatment targets incomparison to non-treatment control targets suggest tentative treatment effects. Whenconsonants related to treatment targets also show significant gains, this further suggeststreatment effects through generalisation’ (2000:32). This clear paradigm differentiates tar-get types enabling a more accurate and systematic approach to the observation of treat-ment effects. With so many sounds to treat to improve articulation in deaf speakers, it isexpedient to bring to light and maximise the process by which the treatment of one ortwo sounds may indirectly and spontaneously transfer to other related but formallyuntreated sounds. This is a response to Gibbon and Paterson’s (2006:275) concern that‘when using EPG, speech and language therapists need to adopt specific strategies to pro-mote generalisation and maintenance’.

Crawford (1995:265) provides a detailed account of her observations of generalisa-tion when training two profoundly deaf children to produce velar stops. Having dem-onstrated successful use of these sounds using EPG therapy where they were eitherabsent or distorted pre-therapy, Crawford observes that both her speakers ‘producedrelatively invariant velar stops, showing no effects of changing vowel environments’.Coarticulation is an index of adult-like motor coordination (Daniloff and Moll 1968;Nolan et al. 1996; Nicolaidis 2004) and provides important cues to listeners in theperception of normal speech. The coarticulatory effects of adjacent vowels on velarconsonants are reported to be relatively large in normal adult speech production(Butcher 1989). It is to be expected perhaps that full generalisation of the newlyacquired velar stops for these speakers would manifest itself in this inter-segmentalvariation as a response to these sounds being produced in varying vowel environmentsin untreated words. Crawford suggests that this non-generalisation is a corollary toincreased length of closure duration for consonantal targets treated with EPG visualfeedback therapy. Nicolaidis (2004) describes some deaf speech as concatenated ratherthan co-articulated. Fine-grained articulatory detail captured by EPG is capable ofdisclosing important information about motor coordination or coarticulation. Verylittle, if anything, is known about the incidence of coarticulation in deaf children’sspeech at any stage of treatment. Much more clinically relevant knowledge isrequired, specifically, its contribution to the process of generalisation during visualfeedback therapy.

With regard to current thinking on how therapists can support maintenance of newspeech skills, Bernthal and Bankson (1998) have put forward a framework of establish-ment, generalisation and maintenance as three phases of a therapy continuum for manage-ment of all speech disorders. Across all clinical populations, there is an axiomatic beliefthat visual feedback therapy is most effective at an early stage of treatment to acquire new



articulatory patterns. Pantelemidou et al.’s (2003:386) comment typifies this view: ‘[our]general aim was to use the EPG to help [the subject] achieve the correct articulation byvisual feedback initially and eventually by tactile and proprioceptive feedback’. In a 2-yearstudy, Dagenais (1992) concluded that there appears to be a 1-year learning plateau withEPG following which conventional therapy can be most effectively used to reinforcenewly learned patterns. The literature on EPG intervention with deaf children eitherconflates generalisation and maintenance, making it hard to extrapolate improvementswhich are carried over post-therapy, or omits to mention it. Of those that do, Parsloe(1998) reports that her participant maintained skills taught by EPG for 3 months, whereasDagenais (1992) observed that 6 months on, all subjects had regressed. More data arerequired to clarify the life-span of maintained patterns following either conventional orvisual feedback therapies in this population. Current understanding puts this at between 3and 6 months.

Conclusion

This review has provided a summary of the articulation errors produced by severely andprofoundly deaf children and has described some approaches to therapy intended toimprove articulatory accuracy for English consonants. The studies on which this review isbased have employed EPG to address these issues. EPG is demonstrated to be a powerfultool in confirming the accuracy of inferences about articulation made from transcriptionin addition to discovering new types of articulation errors previously undescribed in theliterature. It can also be an effective means of improving consonantal targets when usedas a visual feedback device. On the basis of their work on the remediation of intractablespeech disorders in children, Scobbie et al. (2004) recommend ‘the establishment ofspecialist instrumental clinics’ that can provide this facility.

This review of the literature has identified a significant absence of overt understandingof and specific strategies available to clinicians to promote generalisation and maintenanceof learned speech skills in deaf children.

Acknowledgment

I would like to thank two anonymous reviewers for very helpful comments on an earlierdraft of this review.

Short Biography

Dr Lucy Ellis (MPhil Linguistics, University of Cambridge; PhD, Instrumental Phonetics,Queen Margaret University, Edinburgh) is currently Senior Lecturer in Speech & Lan-guage Therapy ⁄English Language & Linguistics, Department of Language & Cognition atthe University College Plymouth, St Mark & St John, UK. Her current teaching respon-sibilities include phonetics, instrumental phonetics, sociolinguistics and diachronic linguis-tics. Her doctoral research applied advanced instrumental techniques for investigatingaspects of the kinematic mechanism for production of normal speech in adults. Morerecently, she has been involved in projects to widen access to EPG by children with cleftpalate and to gain knowledge of disordered patterns of speech in this clinical population.Currently she is working on developing instrumental techniques for the assessment ofspeech motor control in deaf children.

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Note

* Correspondence address: Lucy Ellis, Speech & Language Therapy ⁄ English Language & Linguistics, UniversityCollege Plymouth, St Mark & St John, Derriford Road, Plymouth PL6 8BH, UK. E-mail: [email protected].

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