Electropalatography Research Articles

The electropalatographic study of the coarticulatory effect of vowels on coronal stops in Persian

Using electropalatographic (EPG) data, we study the coarticulatory effect of intervocalic contexts on the Persian coronal stops [t] and [d]. The EPG patterns demonstrate that [d] is produced in a more anterior place than [t], proving the former to be a dentialveolar consonant and the latter to be an alveolar one. The coarticulation index (CI) is calculated for each consonant flanked by the same vowels. The results obtained show that there is no significant difference between [t] and [d], in terms of coarticulation; however, based on the data we have, we can say that [t] is more resistant to coarticulatory effect than [d]. This result is in agreement with previous investigations which propose that laminals show stronger coarticulation resistance than apicals.

Contact Pattern of Alveolar Consonants in the Malay Consonants of Paralysis Subject using Electropalatography

Place of articulation plays an important part to produce different sounds. Besides the place of articulation, tongue is also an active articulator during a continuous speech. During the speech, the tongue moves around creating different sounds when it is placed at different place of articulation. The movement of tongue is controlled by muscles. The lack of muscle movement will produce inactive tongue movement. Paralysis is an example of the muscle weakness in a person resulting in difficulties to move. Paralysis may occur due to several factors including stroke and spinal cord injury (SCI). One of the indirect effects of paralysis is slurred speech and difficulty in speaking. This study aims to determine the contact pattern of five paralysed subjects during speech production of alveolar consonants in the Malay Language. The subjects had paralysis due to different aetiologies and with different medical history backgrounds. All participants were required to produce five single consonants; /d/, /t/, /l/, /n/ and /s/. The data recording was done in a studio laboratory with a soundproof system. The device used for detecting the tongue and hard palate contact in this study was electropalatography (EPG). Subjects were required to wear the artificial palate consists of 62 sensors to detect the tongue and hard palate contact. The speech contact was analysed using Articulate Assistant 1.18TM. The results were then compared with the average contact pattern of Malay speaker which had been obtained in the previous study. In conclusion, the subjects who had frequent treatments produced better articulation and the subjects with positive attitudes produced better articulation during the treatment process.

Tongue-palate contact patterns for Japanese speakers with and without cleft lip and palate

Purpose: Visual feedback therapy, using electropalatography (EPG), has been used to remedy residual articulation errors associated with cleft palate. The tongue-palate contact patterns of typical speakers without cleft palate are usually used as a model. However, it is questionable whether these model patterns are adequate for clients with repaired cleft palate, as their dento-palatal morphology is different from non-cleft speakers. The objective of this study was to investigate the differences in tongue-palate contact patterns between typical speakers with and without cleft palate.Method: EPG data were recorded for alveolar consonants in 15 participants with repaired unilateral cleft lip and palate (UCLP) whose speech was perceptually assessed as typical Japanese. The cumulative templates for each consonant were generated from the maximum contact frame; quantitative analyses (centre of gravity [CoG], variability index) were performed. Fifteen typical Japanese speakers without cleft served as a control group.Result: EPG patterns for each consonant were generally similar between groups. The CoG value of the UCLP group was significantly lower only for /s/. The average variability index was higher for every consonant but the comparisons did not reach significance.Conclusion: The typical tongue-palate contact patterns can be used as a model of visual feedback therapy.

Tongue-palate contact for nasal versus oral stops in speakers with repaired cleft palate

ABSTRACTMost previous studies of speech disorders associated with cleft palate have reported a higher incidence of errors for oral stops, fricatives and affricates compared to nasal stops. However, the results of a recent ultrasound study have raised the possibility that errors affecting nasal consonants might not be as rare as originally thought. A review of the electropalatography (EPG) literature on cleft palate speech has also shown that atypical tongue-palate contact patterns can occur during nasal consonants and that nasal and oral stops are often produced with similar atypical lingual gestures. Therefore, this study investigated the production of nasal stops (/n/and/ŋ/) and the homorganic oral stops (/t/,/d/and/k/,/ɡ/respectively) in eight children with repaired cleft palate using perceptual judgements and evaluation of tongue-palate contact patterns. Results of the perceptual judgements support the findings in the literature that there was a higher per cent phoneme correct for the alveolar nasal (about 90%) than for the oral stops (60–70%). However, there was a low per cent phoneme correct for the velar nasal (about 50%) and the per cent correct as determined by the EPG data was lower than those based on perceptual judgements. Two children showed similar atypical articulatory gestures for the oral and nasal alveolar stops. We discuss the possibility that the nasal errors may be of phonemic as opposed to phonetic origin. The results underscore the importance of considering the phonological dimension of production when assessing the speech of children in this clinical group.

An acoustic and perceptual analysis of children’s adaptation to an electropalatographic sensor

Previous research has investigated adults’ ability to adapt their speech to an electropalatographic (EPG) pseudopalate; however, less is known about how children adapt their speech to the presence of the device. This study examined the acoustic and perceptual effect of an EPG pseudopalate on six elementary school-aged children’s ability to produce the fricatives /s/ and /ʃ/. Speech productions were collected at eight time intervals including before placement of the pseudopalate, at 30-min increments with the pseudopalate in place, immediately following removal of the pseudopalate, and 30 min after removal. The fricative targets were produced in a carrier phrase and during spontaneous conversation. Adaptation was evaluated by measuring the fricative duration, spectral mean, spectral variance, and relative intensity, as well as a series of perceptual ratings from 20 native English listeners. Although there was a relatively high amount of variability among and within speakers, for several children evidence of adaptation was found after 30 minutes. For some participants, full adaptation did not occur until the pseudopalate was removed. Although future research is needed, it is hoped that this study will provide a greater understanding of children’s ability to adapt to the EPG pseudopalate.Previous research has investigated adults’ ability to adapt their speech to an electropalatographic (EPG) pseudopalate; however, less is known about how children adapt their speech to the presence of the device. This study examined the acoustic and perceptual effect of an EPG pseudopalate on six elementary school-aged children’s ability to produce the fricatives /s/ and /ʃ/. Speech productions were collected at eight time intervals including before placement of the pseudopalate, at 30-min increments with the pseudopalate in place, immediately following removal of the pseudopalate, and 30 min after removal. The fricative targets were produced in a carrier phrase and during spontaneous conversation. Adaptation was evaluated by measuring the fricative duration, spectral mean, spectral variance, and relative intensity, as well as a series of perceptual ratings from 20 native English listeners. Although there was a relatively high amount of variability among and within speakers, for several children evidence o...

Use of electropalatography in the treatment of speech disorders in children with Down syndrome: a randomized controlled trial.

Electropalatography (EPG) records details of the location and timing of tongue contacts with the hard palate during speech. It has been effective in treating articulation disorders that have failed to respond to conventional therapy approaches but, until now, its use with children and adolescents with intellectual/learning disabilities and speech disorders has been limited. To evaluate the usefulness of EPG in the treatment of speech production difficulties in children and adolescents with Down syndrome (DS) aged 8-18 years. A total of 27 children with DS were assessed on a range of cognitive and speech and language measures and underwent additional EPG assessment. Participants were randomly allocated to one of three age-matched groups receiving either EPG therapy, EPG-informed conventional therapy or 'treatment as usual' over a 12-week period. The speech of all children was assessed before therapy using the Diagnostic Evaluation of Articulation and Phonology (DEAP) and reassessed immediately post- and 3 and 6 months post-intervention to measure percentage consonants correct (PCC). EPG recordings were made of the DEAP assessment items at all time points. Per cent intelligibility was also calculated using the Children's Speech Intelligibility Measure (CSIM). Gains in accuracy of production immediately post-therapy, as measured by PCC, were seen for all groups. Reassessment at 3 and 6 months post-therapy revealed that those who had received therapy based directly on EPG visual feedback were more likely to maintain and improve on these gains compared with the other groups. Statistical testing showed significant differences between groups in DEAP scores across time points, although the majority did not survive post-hoc evaluation. Intelligibility across time points, as measured by CSIM, was also highly variable within and between the three groups, but despite significant correlations between DEAP and CSIM at all time points, no statistically significant group differences emerged. EPG was an effective intervention tool for improving speech production in many participants. This may be because it capitalizes on the relative strength of visual over auditory processing in this client group. The findings would seem to warrant an increased focus on addressing speech production difficulties in current therapy.

A well-designed single-subject experimental study reveals potential of electroplataography in treating children with misarticulation of /r/

Q Is electropalatography (EPG) an effective method to treat rhotic errors in school-aged children with speech sound disorders?Design: This study adopted a multiple baseline design across five child...

Tongue-Palate Contact Timing during /s/ and /z/ in English

Although numerous studies have investigated supraglottal strategies for signalling voicing in fricatives, there is still no agreement about the precise characteristics of tongue-to-palate contact timing during voiced as opposed to voiceless fricatives. In this study we use electropalatography (EPG) to investigate articulatory and coarticulatory characteristics of tongue-to-palate contact timing during /s/ and /z/ in English. Five typically speaking participants, speakers of Southern British English, produced 500 trochaic words containing the intervocalic alveolar fricatives /s/ or /z/. The time between the start of the frication and the maximum contact at the place of articulation was expressed as a percentage of each fricative's total duration (time to target, TT).This measure was used to analyse articulatory and coarticulatory timing during /s/ and /z/. Data for absolute timing were also presented. The results showed that the time between the start of the frication and the maximum contact point was longer for /s/ than for /z/. This difference was consistent across speakers but was not significant for all of them. The results of the coarticulatory effects showed that the influence of vowel context on TT values for /s/ and /z/ did not differ significantly, but there was a tendency for /z/ to be more resistant to coarticulation effects than /s/.

Efficacy of Electropalatography for Treating Misarticulation of /r/.

The purpose of the present study was to document the efficacy of electropalatography (EPG) for the treatment of rhotic errors in school-age children. Despite a growing body of literature using EPG for the treatment of speech sound errors, there is little systematic evidence about the relative efficacy of EPG for rhotic errors. Participants were 5 English-speaking children aged 6;10 to 9;10, who produced /r/ at the word level with < 30% accuracy but otherwise showed typical speech, language, and hearing abilities. Therapy was delivered in twice-weekly 30-min sessions for 8 weeks. Four out of 5 participants were successful in achieving perceptually and acoustically accurate /r/ productions during within-treatment trials. Two participants demonstrated generalization of /r/ productions to nontreated targets, per blinded listener ratings. The present findings support the hypothesis that EPG can improve production accuracy in some children with rhotic errors. However, the utility of EPG is likely to remain variable across individuals. For rhotics, EPG training emphasizes one possible tongue configuration consistent with accurate rhotic production (lateral tongue contact). Although some speakers respond well to this cue, the narrow focus may limit lingual exploration of other acceptable tongue shapes known to facilitate rhotic productions.

A pressure-sensitive palatograph for speech analysis.

Electropalatography (EPG) is a clinical technique used to monitor contacts between the tongue and the hard palate, thus promoting correct articulation mechanisms. Currently, employed commercial tools have a good resolution but they do not provide contact pressure information. In this work, textile-based sensing technologies were employed to realize an innovative EPG tool able to both maintain the proper spatial resolution and perform quantitative pressure detection. The single sensing unit was developed using a thin polymeric sheet with a central hole, sandwiched between two piezoresistive fabric layers. Under load application, the two textile layers come into contact and the resistance of the sensor reduces significantly, measuring pressure in the range from 0 to 30 kPa. The complete prototype is composed of 62 sensing units disposed in a matrix structure: the dielectric layer contains all the sites arranged in rows and columns, according to the topography of the traditional tools, and this layer presents on both sides strips of piezoresistive textile. The entire system was covered with a thin latex membrane and fixed on a hard custom acrylic palate for the experimental characterization. The system was tested on a healthy subject, confirming the adequacy and effectiveness of the soft sensing technologies for the measuring of the tongue pressure during speech.

Tongue-palatal contact changes in patients with skeletal mandibular prognathism after sagittal split ramus osteotomy: an electropalatography study.

The purpose of this study was to investigate the changes in tongue-palatal contact patterns using electropalatography (EPG) before and after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Nine clients who underwent SSRO for mandibular setback and seven control subjects were participated in this study. Tongue-palatal contact patterns for /t/, /s/ and /k/ production were investigated using EPG before surgery and 3 months after surgery. The mean value of whole total of palate contact (WT) in the maximum contact frame was examined before and after SSRO. The correlation quantity between the change of center of gravity (COG) value and the amount of mandibular setback was also evaluated. The mean value of WT for /t/ and /s/ significantly increased after SSRO, and the EPG pattern became normal. However, a remarkable change in WT for /k/ was not observed, and the mean value was significantly larger in the SSRO group before and after surgery than in the control group. A negative correlation between COG variation and the amount of mandibular setback for /t/ and positive correlation for /s/ was observed. This study demonstrated that tongue-palatal contact patterns for /t/ and /s/ articulation improved clearly after SSRO. There was a significant correlation between COG variation and the amount of mandibular setback. However, no significant change was detected through perceptual assessment before and after SSRO. Further investigation is needed to determine whether these results will change over time.

Utilizing electropalatography to train palatalized versus unpalatalized consonant productions by native speakers of American English learning Russian

Previous research has shown that English-speaking learners of Russian, even those with advanced proficiency, often have not acquired the contrast between palatalized and unpalatalized consonants, which is a central feature of the Russian consonant system. The present study examined whether training utilizing electropalatography (EPG) could help a group of Russian learners achieve more native-like productions of this contrast. Although not all subjects showed significant improvements, on average, the Russian learners showed an increase from pre- to post-training in the second formant frequency of vowels preceding palatalized consonants, thus enhancing their contrast between palatalized and unpalatalized consonants. To determine whether these acoustic differences were associated with increased identification accuracy, three native Russian speakers listened to all pre- and post-training productions. A modest increase in identification accuracy was observed. These results suggest that even short-term EPG training can be an effective intervention with adult L2 learners.

The Use of Electropalatography in the Treatment of Acquired Apraxia of Speech.

This investigation was designed to examine the effects of an articulatory-kinematic treatment in conjunction with visual biofeedback (VBFB) via electropalatography (EPG) on the accuracy of articulation for acquired apraxia of speech (AOS). A multiple-baseline design across participants and behaviors was used with 4 individuals with chronic AOS and aphasia. Accuracy of target speech sounds in treated and untreated phrases in probe sessions served as the dependent variable. Participants received an articulatory-kinematic treatment in combination with VBFB, which was sequentially applied to 3 stimulus sets composed of 2-word phrases with a target speech sound for each set. Positive changes in articulatory accuracy were observed for participants for the majority of treated speech sounds. Also, there was generalization to untreated phrases for most trained speech sounds. Two participants had better long-term maintenance of treated speech sounds in both trained and untrained stimuli. Findings indicate EPG may be a potential treatment tool for AOS. It appears that individuals with AOS can benefit from VBFB via EPG in improving articulatory accuracy. However, further research is needed to determine if VBFB is more advantageous than behavioral treatments that have been proven effective in improving speech production for speakers with AOS.

Electropalatographic (EPG) evidence of covert contrasts in disordered speech

ABSTRACTThe phenomenon of covert contrasts has intrigued researchers and clinicians since it was first identified using instrumental data nearly 50 years ago. The term covert contrast refers to phonological contrasts that listeners do not readily identify and which therefore pass unrecorded in transcription-based studies. Covert contrasts are viewed as significant from theoretical and clinical perspectives. Although influential, there are relatively few instrumental studies of covert contrasts. The studies that do exist are limited to revealing contrasts that manifest in specific phonetic parameters or phonological processes. However, recent studies have provided convincing new evidence that covert contrasts are likely to be widespread in child speech. The purpose of this article is threefold: to review electropalatography (EPG) studies of covert contrasts; to provide EPG examples from the speech of individuals with speech disorders and to discuss the implications in child speech.

Russian palatalized and unpalatalized coda consonants: An electropalatographic and acoustic analysis of native speaker and L2 learner productions

One fundamental aspect of the Russian phonological system is a contrast between palatalized and unpalatalized consonants. This distinction poses a challenge for native English speakers learning Russian as a second language because palatalization is not a feature of their first language (L1) phonology. The present study examined word-final palatalized and unpalatalized consonants produced by native Russian speakers and native English speakers learning Russian. Electropalatographic (EPG) and acoustic recordings were made of six native Russian speakers and six native English speakers, who had significant classroom and immersion experience with Russian. Data from the native Russian speakers suggested that the contrast between palatalized and unpalatalized consonants involves the manipulation of both tongue–palate contact and acoustic properties of the preceding vowel and the consonant itself. The second language (L2) Russian learners showed little if any EPG or acoustic evidence of a contrast between their productions of palatalized versus unpalatalized consonant targets, a finding that suggests that extensive immersion experience alone may not be sufficient for the development of at least some novel L2 contrasts.

Electropalatography for Older Children and Adults with Residual Speech Errors.

Most residual speech errors (RSEs) involve abnormal positioning or movement of the tongue. However, it is not possible under normal circumstances to view directly the actions of the tongue during production of these distorted articulations. The visually inaccessible location of the tongue can often make precise diagnosis difficult in cases of RSEs, and intervention can be a particular challenge for clinicians when speech errors persist in older children and adults. Electropalatography (EPG) is a technique that can provide objective and clinically relevant data about details of tongue articulation during speech. Furthermore, biofeedback with EPG offers the possibility of an effective intervention for RSEs. This tutorial provides an overview of EPG and describes how the technique can contribute to our knowledge and treatment of abnormal tongue-palate contact in older children and adults with RSEs. An illustrative case study of a child with RSEs affecting fricatives and affricates is included.

Generalised EPG treatment effect in a cochlear implant user maintained after 2 years

Purpose: The aim of this study was to evaluate speech therapy using electropalatography (EPG) in home training of persistent articulation errors in a cochlear implant user with hearing impairment. There was a particular focus on aspects of maintenance of training effects and possible transfer to connected speech.Method: The participant was a young woman, deaf from early childhood and a cochlear implant user from pre-school age. Treatment effects were evaluated using a single-subject design with multiple measures.Result: Instrumental and perceptual outcome measures showed a clear improvement in the production of the treatment target /ɡ/ in single words and sentences after 4 months of therapy (17 hours). The results were maintained at 3, 6 and 24 months after intervention. Also, /ɡ/ in connected speech, consisting of text reading and spontaneous speech, showed a significant difference between before and after treatment and at long-term follow-up.Conclusion: The results show that EPG used in home training can be an efficient method for treating persistent speech disorders associated with hearing impairment and that the treatment effect appears to maintain.

Place of articulation of anterior nasal versus oral stops in Croatian

The purpose of this investigation is to analyse the place of articulation of anterior nasal versus oral stops in Croatian. Although there is agreement that placement for /n/ and /td/ is in the anterior region, there is disagreement among different authors about the precise place of articulation for these sounds. Some authors view these targets as sharing identical placement while others view placement of /n/ as more posterior to /td/. In this paper we use electropalatography (EPG) to investigate whether placement for these sounds is the same or different. The speech of six participants was recorded for the purposes of this study. The speech material consisted of 972 VCV sequences (V = /iau/, C = /ntd/). Four EPG indices were analysed: the ACoG measure, the amount of contact at dental and alveolar articulatory zones (dentoalveolar articulation being inferred indirectly), incomplete EPG closures and the lateral contact measure. Coarticulatory effects of vowels on placement were also measured. The results showed that /ntd/ generally shared the place of articulation in the dentoalveolar region, but also that relating quantitative physiological data to specific places of articulation should be done cautiously, taking into account variability in individual productions. The analyses also showed that /n/ had more incomplete EPG closures and a significantly lower amount of lateral contact when compared with /t/ and /d/. The nasal was more variable and showed less coarticulatory resistance in different vowel contexts than /t/ and /d/. The results of this study are discussed in terms of existing descriptions of Croatian consonant system and in light of cross-linguistic findings.

Preliminary Case Studies Investigating the Use of Electropalatography (EPG) Manufactured by CompleteSpeech® as a Biofeedback Toolin Intervention

Preliminary Case Studies Investigating the Use of Electropalatography (EPG) Manufactured by CompleteSpeech® as a Biofeedback Toolin Intervention

Prosodic boundaries effect on segment articulation in standard Chinese: An articulatory and acoustic study

This paper presents an electropalatographic (EPG) and acoustic study of prosodic boundaries effect on the domain-initial segments in Standard Chinese. Two speech sounds, namely, the voiceless unaspirated alveolar stop /t/ and the high front vowel /i/, were studied to examine the domain-initial strengthening in both spatial and temporal dimensions. The articulatory and acoustic parameters of the speech sounds were compared in initial positions of five prosodic constituents in Standard Chinese, namely, a Syllable, a Foot, an Immediate Phrase, an Intonational Phrase, and an Utterance. The results show that: (1) the production of the domain-initial consonantal gesture was prosodically encoded. The linguopalatal contact and the seal duration varied as a function of the prosodic boundary strength. The linguopalatal contact was dependent on the seal duration in a nonlinear fashion. Of the acoustic properties of the domain-initial stop, the total voiceless interval and voicing during closure were found to be reliable acoustic correlates that mark the hierarchical structure of the prosody. (2) At the release moment of the domain-initial stop, no consistent pattern was found to support the domain-initial strengthening. The linguopalatal contact of the vowel immediately following the domain-initial consonant did not show a clear trend of domain-initial strengthening; however, the phonatory features of vowels were indicative of pitch reset at major prosodic boundaries. These indicate that the domain-initial strengthening is restricted on the segment immediately following the boundary. In conclusion Standard Chinese strengthens the phonetic features of the domain-initial segments as a function of boundary strength, which serves as an important way to mark prosodic structure in Standard Chinese.