Electropalatography Research Articles

An EPG Study of Palatal Consonants in Two Australian Languages

This study presents EPG (electro-palatographic) data on (alveo-)palatal consonants from two Australian languages, Arrernte and Warlpiri. (Alveo-)palatal consonants are phonemic for stop, lateral and nasal manners of articulation in both languages, and are laminal articulations. However, in Arrernte, these lamino-(alveo-)palatals contrast with lamino-dental consonants for all three manners of articulation (i.e., it is a double-laminal language), whereas in Warlpiri this laminal contrast does not exist (i.e., it is a single-laminal language). Data are analyzed according to manner of articulation, vowel context and phrase position. Results suggest that in the double-laminal languageArrernte,the (alveo-)palatal articulation is further back than in the single-laminal language Warlpiri, presumably due to the presence of the lamino-dental in theArrernte phoneme inventory. The lateral has the least contact in the back regions of the palate for both languages, but there is no significant difference in contact pattern between the stop and the nasal. However, results tentatively suggest that the nasal (alveo-)palatal is the most likely to show effects of prosodic or vocalic context, and it is suggested that this is due to the less strict airflow requirements for the nasal than for the stop or the lateral.

Effects of medication and subthalamic nucleus deep brain stimulation on tongue movements in speakers with Parkinson's disease using electropalatography: A pilot study

Parkinson's disease (PD) affects speech in the majority of patients. Subthalamic nucleus deep brain stimulation (STN-DBS) is particularly effective in reducing tremor and rigidity. However, its effect on speech is variable. The aim of this pilot study was to quantify the effects of bilateral STN-DBS and medication on articulation, using electropalatography (EPG).Two patients, PT1 and PT2, were studied under four conditions: on and off medication and ON and OFF stimulation. The EPG protocol consisted of a number of target words with alveolar and velar stops, repeated 10 times in random order.The motor part III of the Unified Parkinson Disease Rating Scale (UPDRS) indicated significantly improved motor scores in the ON stimulation condition in both patients. However, PT1’s articulation patterns deteriorated with stimulation whereas PT2 showed improving articulatory accuracy in the same condition.The results revealed different effects of stimulation and medication on articulation particularly with regard to timing. The study quantified less articulatory undershoot for velar stops in comparison to alveolars. Furthermore, the findings provided preliminary evidence that stimulation with medication has a more detrimental effect on articulation than stimulation without medication.

Differentiating Impairment Levels in Temporal Versus Spatial Aspects of Linguopalatal Contacts in Friedreich’s Ataxia

Electropalatography (EPG) was used to describe the pattern of linguopalatal contact and the consonant phase durations exhibited by a group of seven individuals with dysarthria associated with Friedreich's ataxia (FRDA). A group of 14 non-neurologically impaired individuals served as controls. The Reading Electropalatograph (EPG3) system was used to record linguopalatal contact during production of the target consonants (/t/, /l/, /s/, /k/) elicited in five words of CV and CVC construction, with the target consonants in word initial position. These words were embedded into short sentences and repeated five times by each participant. The FRDA group exhibited significantly increased consonant durations compared with the controls while maintaining normal linguopalatal contact patterns. These findings suggest that the articulatory impairment in FRDA manifests as a temporal rather than spatial disturbance.

Electropalatography in home training of retracted articulation in a Swedish child with cleft palate: Effect on articulation pattern and speech

The aim was to evaluate the effectiveness of electropalatography (EPG) in home training of persistent articulation errors in an 11-year-old Swedish girl born with isolated cleft palate. The /t/ and /s/ sounds were trained in a single subject design across behaviours during an eight month period using a portable training unit (PTU). Both EPG analysis and perceptual analysis showed an improvement in the production of /t/ and /s/ in words and sentences after therapy. Analysis of tongue-contact patterns showed that the participant had more normal articulatory patterns of /t/ and /s/ after just 2 months (after approximately 8 hours of training) respectively. No statistically significant transfer by means of intelligibility in connected speech was found. The present results show that EPG home training can be a sufficient method for treating persistent speech disorders associated with cleft palate. Methods for transfer from function (articulation) to activity (intelligibility) need to be explored.

EPG patterns in a patient with phonemic paraphasic errors

Auditorily-detected phonemic paraphasias such as substitutions are said to characterize aphasias such as Wernicke’s and conduction aphasia. However previous research has shown that the articulatory details underlying such substitutions recorded by techniques such as Electropalatography (EPG) may reveal a level of complexity not detected by the auditory analysis alone. Articulatory anomalies such as so-called Misdirected Articulatory Gestures (MAGs) may accompany the production of the substitutions and are variously perceived by listeners. A perceptual study is carried out in which 16 adult listeners rate sounds identified on the basis of EPG analysis as potential substitutions, on a scale from alveolar to velar. Some of the target sounds looked like ‘pure’ substitutions from the EPG patterns and some exhibited MAGs. Listener judgements were not always entirely predictable on the basis of EPG patterns. The occurrence of the anomalous EPG patterns (and the auditory results) is explored further in terms of a modified spreading activation model and implications for clinical management are discussed.

A kinematic investigation of anticipatory lingual movement in acquired apraxia of speech

Background: Apraxia of speech (AOS) is considered a disorder of speech planning or programming. Evidence for this stems from perceptual, acoustic, and electropalatographic investigations of articulation in AOS that revealed a delayed onset of anticipatory vowel gestures. Articulatory prolongation and syllable segregation have been attributed to a disturbance in anticipatory coarticulation. Aims: The aim of the current study was to investigate anticipatory lingual movement for consonantal gestures in AOS, and its impact on absolute and relative speech timing. Methods & Procedures: Tongue-tip movement and tongue-to-palate contact patterns were recorded for three speakers with AOS and a concomitant aphasia (age range = 35–63 years; M = 50.67 years; SD = 14.29) and five healthy talkers (age range = 29–65 years; M = 52.6 years; SD = 14.5) during the phrases “a scarlet” and “a sergeant”, using electromagnetic articulography (EMA) (AG-200 system) and electropalatography (EPG) (Reading Electropalatograph system). Anticipatory lingual movement and speech timing were analysed during the final C1VC/C2 syllable in each of these phrases, where C represented an alveolar or postalveolar consonant. Specifically, tongue-tip displacement was calculated from the onset of release to the end of release of C1 to provide an indication of anticipatory lingual movement. With respect to speech timing, absolute (i.e., duration from time of maximum contact for C1 to time of maximum contact for C2) and relative (i.e., absolute duration expressed as a function of total syllable duration) durational measures were recorded, as was the stability of each. The results recorded for each of the participants with AOS were individually compared to those obtained by the control group. Outcomes & Results: The EMA results indicated that two participants with AOS exhibited reduced anticipatory lingual movement (i.e., greater tongue-tip displacement) during repetitions of “sergeant”; however, all speakers produced a comparable tongue-tip displacement to that produced by the control group during the release of /l/ in “scarlet”. The EPG results indicated that absolute duration was significantly prolonged during the final syllables of both stimuli for each of the apraxic speakers. Equivocal results were reported for relative timing and temporal stability. Conclusions: The results provide some preliminary evidence of reduced anticipatory lingual movement in AOS, and have demonstrated that this can have a significant impact on absolute speech timing. However, measures of relative timing were suggestive of either unimpaired or more extensive coarticulation. Additional research is required to resolve this issue.

Measuring language-specific phonetic settings

While it is well known that languages have different phonemes and phonologies, there is growing interest in the idea that languages may also differ in their ‘phonetic setting’. The term ‘phonetic setting’ refers to a tendency to make the vocal apparatus employ a language-specific habitual configuration. For example, languages may differ in their degree of lip-rounding, tension of the lips and tongue, jaw position, phonation types, pitch range and register. Such phonetic specifications may be particularly difficult for second language (L2) learners to acquire, yet be easily perceivable by first language (L1) listeners as inappropriate. Techniques that are able to capture whether and how an L2 learner’s pronunciation proficiency in their two languages relates to the respective phonetic settings in each language should prove useful for second language research. This article gives an overview of a selection of techniques that can be used to investigate phonetic settings at the articulatory level, such as flesh-point tracking, ultrasound tongue imaging and electropalatography (EPG), as well as a selection of acoustic measures such as measures of pitch range, long-term average spectra and formants.

A perceptual and electropalatographic study of /∫/ in young people with Down's syndrome

Speech production in young people with Down's syndrome has been found to be variable and inconsistent. Errors tend to be more in the production of sounds that typically develop later, for example, fricatives and affricates, rather than stops and nasals. It has been suggested that inconsistency in production is a result of a motor speech deficit. Late acquired fricatives such as /s/ and /∫/ are complex articulations, which may require more precise motor programming and may therefore show highly inconsistent productions. Other factors potentially affecting speech production in this population are abnormal palatal structure, hearing loss, and hypotonia. A group of 20 young people with Down's syndrome were recorded using Electropalatography (EPG), reading a wordlist containing the phrase ‘a sheep’. The wordlist contained seven other phrases and was repeated 10 times. Eight typically developing, cognitively matched children and eight adults were also recorded producing the same data set. Articulatory (EPG pattern analysis) and perceptual analyses of the 10 productions of /∫/ were carried out. /∫/ production was found to be inconsistent in the young people with Down's syndrome, with more errors both in the auditory analysis and articulatory analysis than in the typical sample, which may be due to a motor programming or motor control problem. There were a greater number of errors in the EPG analysis than in the perceptual analysis. This suggests that some young people with DS were able to produce perceptually acceptable /∫/ with atypical EPG patterns. The use of typical, adult-modelled /∫/ EPG patterns in therapy may be inappropriate for some children with DS who present with atypical palatal structures.

Electropalatographic therapy for children and young people with Down's syndrome

Articulation disorders in Down's syndrome (DS) are prevalent and often intractable. Individuals with DS generally prefer visual to auditory methods of learning and may therefore find it beneficial to be given a visual model during speech intervention, such as that provided by electropalatography (EPG). In this study, participants with Down's syndrome, aged 10:1 to 18:9, received 24 individualized therapy sessions using EPG. Simultaneous acoustic and EPG recordings were made pre- and post-intervention during 10 repetitions of a word list containing lingua-palatal consonants. Participants also completed the DEAP phonology sub-test at both time points. Post-treatment, all participants showed qualitative and quantifiable differences in EPG patterns and improvements in DEAP percentage consonants correct. EPG assessment and therapy appears a positive approach for identifying and improving articulatory patterns in children with DS.

Adult speakers' tongue-palate contact patterns for bilabial stops within complex clusters

Previous studies using Electropalatography (EPG) have shown that individuals with speech disorders sometimes produce articulation errors that affect bilabial targets, but currently there is limited normative data available. In this study, EPG and acoustic data were recorded during complex word final /sps/ clusters spoken by 20 normal adults. A total contact (TC) index measured amount of tongue-palate contact during clusters in words such as ‘crisps’. Bilabial closure was inferred from the acoustic signal. The TC profiles indicated that normal adults hold their tongues in a steady /s/-like position throughout the cluster; most speakers (85%, n=17) had no significant difference in TC values during bilabial closure compared to flanking fricatives. The results are interpreted as showing that normal speakers produce double bilabial-alveolar articulations for /p/ in these clusters. Although steady state TC profiles were typical of the group, absolute TC values varied considerably between speakers, with some speakers having up to three times more contact than others. These findings add to the knowledge about normal articulation, and will help to improve diagnosis and treatment of individuals with speech disorders.

Simultaneous measures of electropalatography and intraoral pressure in selected voiceless lingual consonants and consonant sequences of German

This work assessed relationships among intraoral pressure (IOP), electropalatographic (EPG) measures, and consonant sequence duration, in the following obstruents, clusters, and affricates of German: /t/, /sh/, /sht/, and /tsh/. The data showed significant correlations between IOP and percentage of articulatory contact (PC) for all speakers, whereas duration and place of articulation (measured by the EPG center of gravity) contributed less to IOP changes. Speakers differed in the strength of this relationship, possibly reflecting differences in vocal tract morphology or degree of laryngeal abduction. Single-point EPG and IOP measures in fricatives showed consistent correspondences across consonantal contexts, but the relationships for the stops were more complex and reflected positional effects. Temporal compression was observed for both members of the cluster, but only the fricative portion of the affricate. Conversely, coarticulation was observed for both the stop and fricative portion of the affricate, but only for the stop portion of the cluster, possibly reflecting biomechanical constraints. No clear differences were observed in coarticulatory resistance for stops and fricatives. These data contribute to a limited literature on articulatory-aerodynamic relationships in voiceless consonants and consonant sequences, and will provide a baseline for considering longer combinations of obstruents.

An EPG study of the alveolar vs. retroflex apical contrast in Central Arrernte

This study presents EPG (ElectroPalatoGraphic) data from Central Arrernte, an Australian language which has a phonemic contrast between two types of apical consonants: alveolar and retroflex. Results suggest that some apical articulations are highly stable across repetitions, while others are highly variable. More precisely, the most stable and prototypical alveolars (i.e. with a flat EPG contact profile), and the most stable and prototypical retroflexes (i.e. with a forward movement during EPG closure), occur in the phonologically stressed syllable of the word (i.e. the second underlying VC syllable). By contrast, the alveolar in an alveolar-/ ə/-retroflex sequence is highly variable in production. Initial contact is generally retracted for this alveolar, presumably in anticipatory coarticulation with the following retroflex. However, there may also be forward movement of the tongue during closure for the alveolar. It is argued that coarticulation and gesture-spreading models cannot account fully for these data. Instead, the formant structure associated with the later retroflex renders the previous apical ambiguous, and speaker/listeners may then re-interpret the first apico-alveolar as being retroflex. It is therefore possible that in Arrernte, the apical contrast is neutralized not in word-initial position per se (as is typical of most languages containing this contrast), but in the weak initial (V)C syllable of the word.

Articulatory characteristics of coronal consonants in Argentine Spanish: An electropalatographic study.

Previous articulatory investigations of Spanish have been largely limited to its Peninsular varieties. This study uses electropalatography (EPG) to investigate articulatory characteristics of coronal consonant contrasts in Argentine Spanish as part of a larger project examining phonetic variation across Spanish dialects. Simultaneous EPG and acoustic data were collected from four female speakers of Buenos Aires Spanish reading sentences with various intervocalic coronal consonants. Results revealed consistent differences in terms of anterior/posterior tongue placement and the amount of linguopalatal contact with the primary distinction between (denti-)alveolar and post-alveolar articulations within the classes of stops/affricates, fricatives, nasals, and laterals/rhotics. Inter-speaker variation was observed, however, in the articulation of some consonants, namely, in the apical or laminal realization of the post-alveolar fricative and in the palatal or palatalized alveolar realization of the post-alveolar nasal. These findings diverge from those reported for Peninsular Spanish [A. M. Fernández Planas, Estudios de fonética experimental, 16, 11–80 (2007)], revealing some dialectal differences in the degree of fronting of denti-alveolars. Additionally, results suggest a sound change in progress in Argentine Spanish, such as the depalatalization of the palatal nasal. [Work supported by Connaught, University of Toronto.]

Articulation Characteristics of Severely and Profoundly Deaf Children and Approaches to Therapy: A Review of the Electropalatography Literature

AbstractThis article provides a concise review of (i) the segmental articulation errors produced by severely and profoundly deaf children and (ii) the approaches to therapy carried out to remediate these errors. In both cases, evidence is gathered from studies using electropalatography (EPG), an instrumental technique which provides a direct articulatory display of the timing and location of contact between the tongue and the hard palate during speech. Attention is paid to what is known about the generalisation and maintenance of improvements in speech production following EPG visual feedback therapy.

Electropalatography for articulation disorders associated with cleft palate

Cleft palate is the most common congenital deformity of the face. It could affect speech acquisition, resulting in articulation errors that could persist into adulthood. Electropalatography (EPG) has been used in speech therapy with individuals who have articulation problems that are unresponsive to "standard treatment" procedures. To determine the effectiveness of speech intervention using electropalatography (EPG) for treating articulation errors in individuals with repaired cleft palate. The following databases were searched: CENTRAL 2008 (Issue1), MEDLINE 1966 to March 2008, EMBASE 1974 to March 2008, CINAHL 1982 to March 2008, PsycINFO 1967 to March 2008 and eight other databases. We handsearched Clinical Linguistics and Phonetics (1987 to 2008, Issue 2), Cleft Palate Journal/ Cleft Palate-Craniofacial Journal (1980 to 2008, Issue 1), and the International Journal of Language and Communication Disorders (1980 to 2008, Issue 1). We searched the EPG bibliography (Gibbon 2007). We reviewed reference lists of relevant articles and approached researchers to identify other possible published and unpublished studies. Randomised controlled studies comparing EPG intervention to no treatment, delayed treatment, "standard treatment", or alternative treatment techniques for managing articulation problems associated with cleft palate in children or adults. One author searched the titles and abstracts and assessed trial quality. A second author checked judgements; disagreement was resolved through discussion. Three authors were available to examine any potential trials for possible inclusion in the review. One trial using parallel design met the inclusion criteria of this review; no meta-analysis was performed. The study reported that fewer therapy sessions were needed to achieve the treatment goals for the EPG therapy and frication display method (N = 2), followed by EPG therapy (N = 2) and "standard treatment" (N = 2). The included trial was a small-scaled study and there were serious limitations in the design and methodology (e.g. allocation concealment was unclear, blinding of outcome assessor(s) was not ensured, few quantitative outcome measures were used, and the results were not reported as planned). Therefore, the current evidence supporting the efficacy of EPG is not strong and there remains a need for high-quality randomised controlled trials to be undertaken in this area.

On the relationship between palate shape and articulatory behavior

In this study the acoustic and articulatory variabilities of speakers with different palate shapes were compared. Since the cross-sectional area of the vocal tract changes less for a slight change in tongue position if the palate is domeshaped than if it is flat, the acoustic variability should be greater for flat palates than for domeshaped ones. Consequently, it can be hypothesized that speakers with flat palates should reduce their articulatory variability in order to keep the acoustic output constant. This hypothesis was tested on 32 speakers recorded via electropalatography (EPG) and acoustics. The articulatory and acoustic variability of some of their vowels and /j/ was measured. Indeed, the results show that the speakers with flat palates reduce their variability in tongue height. There is no such trend in acoustic variability.

The use of electropalatography (EPG) in the assessment and treatment of motor speech disorders in children with Down's syndrome: Evidence from two case studies

Background: Many children experience significant difficulties in developing key aspects of speech. For some, these communication difficulties are compounded by co-occurring intellectual disabilities.Method: This paper presents two case studies from a larger on-going longitudinal study of the effectiveness of using electropalatography (EPG) to address the intelligibility problems experienced by many children and young people with Down's syndrome (DS). EPG, an innovative computer-based tool for assessing and treating speech motor difficulties, enables the speaker to ‘see’ the placement of his or her tongue during speech and to attempt to correct any lingual palatal errors.Results: This visual supplementation of auditory feedback offers potential therapeutic benefits for children with intellectual disabilities, many of whom show relative strengths in visual vs. auditory and simultaneous vs. sequential processing. EPG also provides therapists with an objective measure of articulatory ability.Conclusions: Findings from these two case studies demonstrate the potential utility of EPG in both the assessment and treatment of speech motor disorders in DS.

Articulatory evidence for feedback and competition in speech production

We report an experimental investigation of slips of the tongue using a Word Order Competition (WOC) paradigm in which context (entirely non-lexical, mixed) and competitor (whether a possible phoneme substitution would result in a word or not) were crossed. Our primary analysis uses electropalatographic (EPG) records to measure articulatory variation, and reveals that the articulation of onset phonemes is affected by two factors. First, onsets with real word competitors are articulated more similarly to the competitor onset than when the competitor would result in a non-word. Second, onsets produced in a non-lexical context vary more from the intended onset than when the context contains real words. We propose an account for these findings that incorporates feedback between phonological and lexical representations in a cascading model of speech production, and argue that measuring articulatory variation can improve our understanding of the cognitive processes involved in speech production.

Norwegian retroflex stops in a cross linguistic perspective

In this paper, Norwegian retroflex stops are investigated through the combined use of electropalatography (EPG) and electromagnetic articulography (EMA), with extensive and detailed data from four informants. Cross linguistic investigations have shown considerable articulatory variation in retroflex consonants regarding both place of articulation and tongue configuration, making it difficult to establish common articulatory characteristics for these consonants. Through our detailed articulatory investigation, we were able to identify one characteristic only that was always present in retroflex stops in Norwegian, namely an apical articulation. Other characteristics often found in retroflexes, like a posterior place of articulation, a bending up (retroflexion) of the tongue tip, a flat tongue middle, and a forward movement of the tongue tip after the release of the stop (‘flapping out’), were found only in some contexts or in some individuals. Overall, the extensive articulatory variation in retroflexes often found in languages with relatively small inventories of coronal consonants was confirmed in our data.

Intervention for lateral /s/ using electropalatography (EPG) biofeedback and an intensive motor learning approach: a case report

Visual biofeedback using electropalatography (EPG) has been beneficial in the treatment of some cases of lateral /s/ misarticulation. While EPG intervention is motorically based, studies have not commonly employed a motor learning approach to treatment. Furthermore, treatment success is measured primarily by change to EPG tongue-palate contact patterns and listener ratings conducted by speech-language therapists. Studies have not commonly measured articulatory change without the palate in-situ using acoustic analysis and non-professional listeners. To determine if an intensive treatment programme including both visual biofeedback (EPG) and traditional articulation techniques within a motor learning paradigm would result in functional improvement to /s/ articulation in an 11-year-old girl with persistent lateral misarticulation. Treatment involved 12 sessions of therapist-delivered treatment over 4 weeks followed by a 6-week home programme. Outcomes of the treatment programme were measured primarily using naive listener ratings and acoustic analysis of /s/ spectra. Improvements to both the perceptual and spectral characteristics of /s/ articulation occurred following the treatment programme. The study highlighted the benefit of an intensive approach to intervention incorporating both visual biofeedback and traditional articulation approaches. The inclusion of a 6-week structured home-programme was beneficial and resulted in consolidation of treatment gains.