Electropalatography Research Articles

Misarticulation Caused by Abnormal Lingual-Palatal Contact in Patients with Cleft Palate with Adequate Velopharyngeal Function

Misarticulations produced by three patients with cleft palate (2 isolated cleft palate; 1 unilateral cleft lip, alveolus, and palate) who attained adequate velopharyngeal function and normal palatal vault by early surgical repairs were examined using electropalatography (EPG) and sound spectrography (SG). Common characteristics of lingual-palatal contact in which the contact area was broader and/or was more posterior than normal were observed. These misarticulations can be divided into three types based on the direction of the breath emission: palatalized misarticulation (in which air passes along the midline of the palate), lateral misarticulation (in which air flows laterally through the occluded dental arch), and nasopharyngeal misarticulation (in which air flows out the nose). These three are considered to be similar to intractable posterior pattern of articulation in cleft palate patients previously reported. However, these types of misarticulations can be produced by cleft patients who have achieved adequate velopharyngeal function and normal palatal vault.

Misarticulation Caused by Abnormal Lingual-Palatal Contact in Patients with Cleft Palate with Adequate Velopharyngeal Function

Misarticulations produced by three patients with cleft palate (2 isolated cleft palate; 1 unilateral cleft lip, alveolus, and palate) who attained adequate velopharyngeal function and normal palatal vault by early surgical repairs were examined using electropalatography (EPG) and sound spectrography (SG). Common characteristics of lingual-palatal contact in which the contact area was broader and/or was more posterior than normal were observed. These misarticulations can be divided into three types based on the direction of the breath emission: palatalized misarticulation (in which air passes along the midline of the palate), lateral misarticulation (in which air flows laterally through the occluded dental arch), and nasopharyngeal misarticulation (in which air flows out the nose). These three are considered to be similar to intractable posterior pattern of articulation in cleft palate patients previously reported. However, these types of misarticulations can be produced by cleft patients who have achieved adequate velopharyngeal function and normal palatal vault.

EPG data reduction methods and their implications for studies of lingual coarticulation

The technique of electropalatography (EPG) provides detailed spatio-temporal information on tongue contacts with the hard palate during continuous speech. In most available versions of the technique the contact data are obtained at a sampling rate of 100–200 Hz from a number of electrodes (usually more than 60) mounted on the surface of an artificial palate. Detailed qualitative information is available from appropriate computer processing, but for many purposes, e.g. for statistical analysis, quantitative data are required. This paper reviews some recent methods of EPG data reduction including numerical indices of contact patterns.

Visual display of tongue‐palate contact: Electropalatography in the assessment and remediation of speech disorders

The technique of electropalatography (EPG) records the location and timing of tongue contacts with the hard palate during continuous speech. Recent developments in hardware and software design of the Reading electropalatograph are described and applications of the technique in assessment and remediation of a variety of speech disorders are outlined. In assessment, it is shown that EPG can provide insights into possible origins of auditorily perceived errors, and case descriptions illustrate how this information can lead to a more rationalised approach to treatment. In therapy, the provision of real-time visual feedback of tongue movement can be effective in the remediation of certain types of intractable speech problems. Finally, the importance of techniques such as EPG in the objective evaluation of treatment procedures is discussed in the light of the increasing demand for accountability within the speech therapy service.

Lingual activity in two speech‐disordered children's attempts to produce velar and alveolar stop consonants: Evidence from electropalatographic (EPG) data

Research is accumulating to suggest that, in the process of phonological acquisition, children pass through a stage of producing subphonemic acoustic cues to distinguish target phonemic contrasts. These subtle, or covert, distinctions occur unnoticed by a transcriber, yet their existence is viewed as having potentially important theoretical and clinical implications. In this study, the technique of electropalatography (EPG) was used to investigate tongue placement in two speech-impaired subjects (sisters), during their attempts to produce alveolar/velar stop contrasts, and their EPG printouts compared to those of a normal subject. Transcription of the impaired subjects' speech showed that, whilst one was able overtly to produce the contrast, the other was using the phonological process of alveolar backing, and so was judged not to have the contrast. However, contrary to the predictions made based on the auditory transcription, the EPG data revealed that both children were making similar, and clearly distinguishable, lingual-palate contacts for the two places of articulation. Examination of the data revealed that the subject who was overtly producing the contrast was able to control the precise sequence of tongue movements necessary in the release phase of the two classes of stops. This critical stage in alveolar/velar stop production had not been mastered by the subject who was not producing a perceptible distinction. The clinical relevance of these findings is discussed.

Modifying abnormal tongue patterns in an older child using electropalatography

This case study describes the investigation and treatment of a child with abnormal production of /s/ and lzl, using the instrumental technique of electropalatography (EPG). Children such as the one described can be resistant to treatment using conventional approaches, with the result that the difficulties may persist for years. EPG appears to be a potentially valuable tool that provides the clinician with more detailed information on tongue/palate contact, and offers the client important visual feedback for instantaneous monitoring, which helps to establish permanent modification of tongue placement patterns.

Coarticulation effects in American English velar and alveolar stop consonants: An electropalatographical and acoustical analysis

Coarticulation effects of post-consonantal vowels on the place of tongue contact for American English velar and alveolar stop consonants were examined through simultaneous measurements with a new type of electropalatography (EPG) and with spectral analysis. The EPG system, developed by the author, has 49 electrodes, and is used to observe lingual contact with the soft palate, hard palate, and upper incisal teeth. It can record the palatograms at a 7.8-ms frame interval. The resulting palatograms can be compared with acoustic spectra made from simultaneous speech recordings. One American male subject produced VCV utternances in which the consonants were /k/, /g/, /t/, and /d/, and the vowels were /a/, /o/, /u/, /e/, and /i/. The results confirm that the tongue contact position for American English velar stop consonants is more strongly influenced by the vowels following it than for alveolar stop consonants. The value of F2 around the release burst was consistent with the strong coarticulation effects observed with the EPG.

The use of instrumental phonetics in the assessment and remediation of three cleft palate children with late repair of the hard palate

Cleft palate children with relatively late repairs of the hard palate often manifest abnormal speech patterns which can severely disrupt intelligibility. However, the precise nature of these abnormal patients is often difficult to determine by impressionistic judgments, and their problems are frequently ongoing and resistant to conventional therapy. In this study we investigated the speech of three such children whose anterior fistulas were successfully closed at 7,5.5 and 5 years respectively. The instrumental techniques of pneumotachography (for measuring air pressure/flow) and electropalatography (for recording spatial and temporal details of tongue contact on the hard palate) were used to assess the children’s speech. Hearing was normal and resonance was within normal perceptual limits, but the pressure/flow measurements did reveal some slightly abnormal closure patterns of the velopharyngeal port. Electropalatographic (EPG) results confirmed that tongue contacts were frequently abnormal, particularly on those sounds involving anterior placement of the tongue in the alveolar region. EPG patterns showed generally more extensive contact than normal for alveolar stops and retracted contact patterns particularly for fricative CT). Abnormal velar contact was present for bilabial stops in one child. It was hypothesised that alveolar fricatives are most likely to be impaired because they are generally more complex and involve greater precision in muscular control and kinaesthetic feedback. Articulatory problems could be related to possible early hearing loss, the relatively late repair, presence of scar tissue interfering with tactile feedback, and shape of the palate. Therapy using EPG as a visual feedback device was successful in improving articulatory placements in all three children.

EPG from square one: An overview of electropalatography as an aid to therapy

This paper describes the use of electropalatography (EPG) as a visual feedback device for the treatment of a variety of articulation disorders. Both children and adults with developmental and acquired problems of speech were assessed and treated using EPG; the results are described and evaluated. Treatment guidelines were formulated and are presented together with the individual programmes developed for the subjects, which combine new techniques with more conventional therapy methods. The paper presents an overview of the use of EPG in speech therapy to date.

Clinical applications of EPG to Japanese cleft palate and glossectomy patients

Electropalatography (EPG) has been used to study articulatory movements in 25 cleft palate cases and three glossectomy cases producing Japanese VCV syllables. In those with cleft palate, three recently defined types of misarticulation, Japanese palatalized articulation, Japanese lateral misarticulation and Japanese nasopharyngeal articulation, were confirmed objectively. In each case of glossectomy, the area of palato-lingual contact at the moment of maximum contact appears to be limited to some definite region of the palate, even for different consonants. However, the degree of intelligibility of each sound is quite different depending on the manner of articulation. These results show that EPG is a useful diagnostic device for analyzing the articulation disorders in cleft palate and glossectomy.

Combining displays of EPG and automatic segmentation of speech for clinical purposes

The development of dynamic electropalatography (EPG) and automatic segmentation of speech has been motivated by the requirements of different end users, although both have been used for clinical purposes. EPG is used in experimental phonetics to record lingual-palatal contacts during continuous speech and there is also a growing interest in its use in speech therapy. Automatic segmentation and labelling is a technique which assigns acoustic-phonetic labels to continuous speech. It has been claimed to be useful as a front end in automatic speech recognition, and automatic language recognition. On the clinical side, coarse phonetic features have been used successfully in therapy to provide visual feedback for the deaf, such as those used in the dedicated hardware system called C Speech and also to assist in lipreading. At Leeds University, a display of automatically produced broad phonetic classes is being developed as a potential visual feedback system for the deaf. To make the system more comprehensive an...

Deviant articulation in a cleft palate child following late repair of the hard palate: A description and remediation procedure using electropalatography (EPG)

Older children with repaired cleft palates who have unresolved speech difficulties present the clinician with a particular challenge, since they do not respond readily to conventional therapy techniques (Noordhoff, Kuo, Wang, Huang and Witzel, 1987). This study describes the use of EPG in the investigation and remediation of a 13-year-old cleft palate boy, who presented with an apparently intractable posterior pattern of articulation. This subject also had received delayed hard palate surgery, which took place at the age of 11 years. EPG printouts of palato-lingual patterns provided information that both confirmed perceptual judgements and also revealed details of articulatory movements that could not be detected from the acoustic signal. A treatment procedure using EPG as a visual feedback device was successful in establishing correct tongue placements. Possible relevant aetiological factors relating to the development of posterior tongue placements are discussed.

New developments in electropalatography: A state-of-the-art report

Recent developments in Electropalatography (EPG) as a technique for investigating spatio-temporal details of tongue contacts with the hard palate in both normal and pathological speech are reviewed...