Tongue/palate contact for the production of /s/ and /z/

Productions of /s/ and /z/ by ten adult speakers were investigated using the electropalatograph (EPG). The participants, ten speech researchers who spoke English as their first language, recorded productions of /s/ and /z/ in nonsense and real words. The maximum contact frame was used as the point of reference to compare tongue/palate contact for each production. Each speaker had alveolar contact, lateral bracing and most had a midline groove for both /s/ and /z/; however, the array of contacted electrodes was unique for each speaker. The groove widths and lengths ranged from 0–3 electrodes. There was significantly greater alveolar tongue/palate contact for /z/ compared to /s/ in word‐initial position, but not in word‐final position for the following measures: alveolar palatal contact, medial groove width, medial groove length. However, when measures of total palate contact and centre of gravity were considered, there was a complex interaction between the phonemes /s/ and /z/, coarticulation with the vowel, word position, and word context (real and nonsense words).     

Tongue/palate contact for the production of /s/ and /z/

Productions of /s/ and /z/ by ten adult speakers were investigated using the electropalatograph (EPG). The participants, ten speech researchers who spoke English as their first language, recorded productions of /s/ and /z/ in nonsense and real words. The maximum contact frame was used as the point of reference to compare tongue/palate contact for each production. Each speaker had alveolar contact, lateral bracing and most had a midline groove for both /s/ and /z/; however, the array of contacted electrodes was unique for each speaker. The groove widths and lengths ranged from 0-3 electrodes. There was significantly greater alveolar tongue/palate contact for /z/ compared to /s/ in word-initial position, but not in word-final position for the following measures: alveolar palatal contact, medial groove width, medial groove length. However, when measures of total palate contact and centre of gravity were considered, there was a complex interaction between the phonemes /s/ and /z/, coarticulation with the vowel, word position, and word context (real and nonsense words).     

Electropalatographic specification of Croatian fricatives /s/ and /z/

Electropalatographic specification of alveolar fricatives in Croatian is aimed at providing speech therapists with normative data about the range of acceptable productions of /s/ and /z/ in adult speakers of Croatian. Four variables were analysed: place of articulation, total contact, groove width and hold phase duration. Intra- and inter-speaker variability for each variable was analysed. Lingual palatal cues for voicing difference were also quantified and discussed. Results show that Croatian /s/ and /z/ are alveolar and not dental as previously reported. The comparison between the voiced and the voiceless fricative shows that durational measures provide the best differentiation. The voiceless counterpart is significantly longer. The difference between voiced and voiceless is also found in the total contact, with /z/ having more contact in the anterior four rows of electrodes, while /s/ has more contact in the posterior four rows of electrodes. This difference is also reflected in the anterior and the posterior groove widths. Possibilities of using these results as normative data for the diagnosis and treatment of atypical articulation of /s/ and /z/ are discussed.     

A comparative study of contractile responses in diaphragm muscles of normal and dystrophic (C57BL6Jdy2Jdy2J) mice

Potassium and caffeine contractures of isolated small bundles (100 to 200 μm diameter) of muscle fibers isolated from the diaphragm of normal and dystrophic ($\text{C57BL}\text{6J}\text{dy}{}^{\mathrm{2J}}\text{dy}{}^{\mathrm{2J}}$) mice were compared. In diaphragms of pathologic mice (3 to 5 months old) the resting potential, the characteristics of the twitch, and some histological examinations were typical of dystrophic muscles. The slopes of the relationships between the steady membrane potential and log [K]₀ were similar for the two types of cells. In 110 mM and 146 mM K there were no significant differences in the time course of the contractures and reduction in [Ca]₀ decreased the time to peak and the time constant of relaxation to the same extent; the relative efficiency of [Mg]₀ compared with [Ca]₀ was equivalent. Repriming of K contractures at different external calcium concentrations indicated that the normal diaphragm did not have any special advantage. The exposure of isolated strips to a solution containing caffeine resulted in a similar increase of the strength of the regularly evoked twitch responses. However, the contractures elicited by 1.25 to 20 mM caffeine showed a subsensitivity of the dystrophic diaphragm (K_mDys = 9.3 K_mN) and the rate of relaxation was significantly slower than in normal muscle (in 20 mM caffeine, 50% decay time for normal muscle was 25.2 ± 7.6 s and for dystrophic muscle 54.8 ± 11.2 s. THese results suggest an absence of major alterations in the mechanism of excitation-contraction coupling associated with dystrophy, except for a change in the specific element of the sarcoplasmic reticulum where caffeine acts.     

Rate and extent of functional reinnervation in fast-twitch and slow-twitch muscles of the dystrophic mouse (C57Bl6Jdy2jdy2j)

The extent of functional reinnervation of fast-twitch extensor digitorum longus muscle in dystrophic and normal mice was determined at various times after nerve transection. Functional reinnervation was assessed by measuring the twitch tension evoked by stimulation of the nerve central to the site of transection. In control mice aged 4 to 6 weeks at the time of denervation, complete reinnervation was observed after 6 weeks. In dystrophic mice of the same age reinnervation was clearly impaired. The ratio of functional innervation of the operated leg to that of the contralateral unoperated leg was only 0.62 after 6 weeks. In older dystrophic mice (4 to 6 months at the time of nerve transection) the reinnervation ratio was even lower, 0.43 after 12 weeks. Reinnervation of slow-twitch soleus muscle was assessed 8 weeks after denervation and was also found to be reduced in the older dystrophic animals. The extent of reinnervation was reflected in the measured values of muscle weight, twitch tension per unit wet weight, and twitch time course. The impairment of reinnervation of dystrophic muscle is consistent with, but not proof of, a neurogenic defect in murine muscular dystrophy.     

Articulatory placement for /t/, /d/, /k/ and /g/ targets in school age children with speech disorders associated with cleft palate

This study used electropalatography (EPG) to identify place of articulation for lingual plosive targets /t/, /d/, /k/ and /g/ in the speech of 15 school age children with repaired cleft palate. Perceptual judgements indicated that all children had correct velar placement for /k/, /g/ targets, but /t/, /d/ targets were produced as errors involving palatalization or velar placement. An EPG classification scheme identified alveolar, palatal and velar placement. Articulations involving contact in alveolar and velar regions simultaneously were identified as alveolar velar double articulations (AVDAs). The classification revealed that AVDAs were relatively frequent, with 28% of alveolar and 12% of velar targets affected, and ten out of the 15 children produced one or more of these abnormal articulations. The majority of children had variable placements, with alveolar more variable than velar targets. The positive finding from the EPG data revealed that most children with perceptual errors for /t/, /d/ were able to make closure in the alveolar region during at least some of their attempts to articulate these targets. It is argued that appropriate analysis and interpretation of EPG data provide clinically relevant information about tongue placement in cleft palate speech.     

Articulatory placement for /t/, /d/, /k/ and /g/ targets in school age children with speech disorders associated with cleft palate

This study used electropalatography (EPG) to identify place of articulation for lingual plosive targets /t/, /d/, /k/ and /g/ in the speech of 15 school age children with repaired cleft palate. Perceptual judgements indicated that all children had correct velar placement for /k/, /g/ targets, but /t/, /d/ targets were produced as errors involving palatalization or velar placement. An EPG classification scheme identified alveolar, palatal and velar placement. Articulations involving contact in alveolar and velar regions simultaneously were identified as alveolar velar double articulations (AVDAs). The classification revealed that AVDAs were relatively frequent, with 28% of alveolar and 12% of velar targets affected, and ten out of the 15 children produced one or more of these abnormal articulations. The majority of children had variable placements, with alveolar more variable than velar targets. The positive finding from the EPG data revealed that most children with perceptual errors for /t/, /d/ were able to make closure in the alveolar region during at least some of their attempts to articulate these targets. It is argued that appropriate analysis and interpretation of EPG data provide clinically relevant information about tongue placement in cleft palate speech.     

Comparisons of neural and pacing activities in intestinal segments from W/W++ and W/WV mice

We studied pacing and neurotransmission in longitudinal (LM) and circular muscle (CM) in intestine of W/W++ and W/W(V) mice. Electrical field-stimulation (EFS) of nerves in LM segments was more inhibitory in W/W(V) mice than in W/W++ mice. No inhibitory input to CM segments of W/W(V) mice was found. The EFS, after nerve block, entrained segments of both W/W++ and mutant mice with 10 ms pulses, and entrained those of mutant mice more readily at 1 and 3 ms pulses. Pacing with external electrodes did not depend on interstitial cells of Cajal in the myenteric plexus (ICC-MP). 2-Aminoethoxydiphenyl borate (2-APB), putative antagonist at IP3 receptors, store-operated channels and the Sacro-endoplasmic reticulum Ca2+ ATPase pump, reduced frequency and amplitudes of pacing of LM segments from W/W(V) mice as it did in BALB/c mice. Thus, its actions may not require ICC-MP. SKF 96365, a putative inhibitor of store-operated channels, reduced frequencies and amplitudes of intestinal segments in W/W++ mice at 10 or 30 micromol L-1. This resulted from blocking L-Ca2+-channels. Thus, no evidence was found that store-operated channels play a role in pacing. In LM segments of W/W(V), SKF 96365 had no effects on frequency of contractions. We conclude, results from models of severely reduced systems may not be applicable to intact ICC networks.     

Metrical/syllabic factors in English allophony: dark /l/

This paper presents a single-subject case study illustrating the need to closely examine effects of dialect from syllable position on l-colouring, and the effects of domain-initial strengthening in General American English. Most investigators report lighter /l/ tokens in syllable onsets and darker tokens in coda positions in isolated words. The present study demonstrates an enhanced darkened onset /l/ in front vowel prosodic word (PW) boundaries, but lighter codas at PW-internal boundaries. We address the importance for clinicians of recognizing the impact of prosody on restructuring syntactic boundaries and its consequent effects on /l/ articulation.     

Interictal 99Tcm HMPAO SPECT and 1H MRS in Children with Temporal Lobe Epilepsy

Summary: Purpose: To understand the pathological basis of focal hypoperfusion seen on interictal ⁹⁹Tc^m hexamethylpropyleneamine oxime (HMPAO) single-photon-emission computed tomography (SPECT) in intractable temporal lobe epilepsy, and to determine why the technique may be misleading in the localization and lateralization of the seizure focus in some cases.
Methods: Interictal ⁹⁹Tc^m HMPAO SPECT and proton magnetic resonance spectroscopy (¹H MRS) of the mesial temporal regions were performed in 14 children with intractable temporal lobe epilepsy not caused by a foreign tissue lesion.
Results: Hypoperfusion of one temporal lobe ipsilateral to the seizure focus was demonstrated in 10 (71%) of the children; ¹H MRS correctly lateralised in eight of these 10. No asymmetry of perfusion of the anterior temporal regions was seen in the remaining four children; on ¹H MRS, three of these were bilaterally abnormal but nonlateralising. Repeated SPECT and ¹H MRS in three children demonstrated changes over time, the findings from the two techniques being consistent with each other on both the initial and the repeated scans.
Conclusions: Abnormalities demonstrated by ¹H MRS correlate well with those seen on interictal SPECT and can help to understand the pathologic basis of these SPECT abnormalities. Furthermore, the presence of bilateral damage can result in an absence of perfusion asymmetry on interictal SPECT.     

Leukotrienes B4 and C4 in MS

Release of leukotriene B4 (LTB4) and leukotriene C4 (LTC4) from neutrophils and platelet-neutrophil suspensions in response to ionophore A23187 was measured in 12 multiple sclerosis (MS) patients and 8 healthy volunteers. LTC4 release from neutrophils, as well as from platelet-neutrophil suspensions, was significantly decreased in MS patients compared with the controls. There was no significant difference in the release of LTB4 between MS patients and controls. The findings suggest that permanent stimulation of platelets and neutrophils e.g., by encephalitogenic peptide leads to continuous LTC4 release with subsequent depletion of intracellular substrates serving as precursors for the formation of 5-lipoxygenase products. Since the target of microvascular actions of LTC4 are postcapillary venules, the release of this sulfidopeptide leukotriene might play a pathogenetic role in the formation of MS lesions.     

Adaptation strategies in perturbed /s/

The purpose of this work is to investigate the role of three articulatory parameters (tongue position, jaw position and tongue grooving) in the production of /s/. Six normal speakers' speech was perturbed by a palatal prosthesis. The fricative was recorded acoustically and through electromagnetic articulography in four conditions: (1) unperturbed, (2) perturbed with auditory feedback masked, (3) perturbed with auditory feedback available and (4) perturbed after a 2-week adaptation period. At the end of the adaptation, speakers produced more high-frequency noise while either having a higher jaw position or more grooving of the tongue or both. We discuss the potential clinical implications of the results with regard to the role of jaw height and tongue grooving in the treatment of impaired /s/.     

Adaptation strategies in perturbed /s/

The purpose of this work is to investigate the role of three articulatory parameters (tongue position, jaw position and tongue grooving) in the production of /s/. Six normal speakers' speech was perturbed by a palatal prosthesis. The fricative was recorded acoustically and through electromagnetic articulography in four conditions: (1) unperturbed, (2) perturbed with auditory feedback masked, (3) perturbed with auditory feedback available and (4) perturbed after a 2-week adaptation period. At the end of the adaptation, speakers produced more high-frequency noise while either having a higher jaw position or more grooving of the tongue or both. We discuss the potential clinical implications of the results with regard to the role of jaw height and tongue grooving in the treatment of impaired /s/.     

Is /h/ phonetically neutral?

Use of /h/ in the phrase, ‘Say /hVC/ again’ has been tacitly assumed to provide a neutral phonetic context in which to study the articulatory characteristics of speech either preceding or following /h/ articulation. Yet, assessment of the stability or neutrality of /h/ has gone untested. The current study sought to determine whether articulation of /h/ differs according to sex and language accent, as well as to examine its influence on subsequent vowel articulation. Selected acoustic features of /hVC/ were measured in 40 speakers of American English (AE) and 40 speakers of Mandarin-accented English (MAE). Results of an analysis of /h/ duration revealed no sex differences within each language group, however considerable variation was found according to accented vs unaccented English. Clear sex differences were found for the production of /?/, occurring more often among male speakers regardless of language variety. Considerable variation in production of /?/ was found between language groups. Analysis of vowel formant frequencies immediately following /h/ articulation indicated minimal coarticulatory effects for both AE and MAE speakers. The present results appear to support the suggestion that /h/ is not exclusively sex-linked and may indeed vary according to non-biological factors. In spite of these variations, /h/ articulation appears to have a negligible influence on neighbouring vowel articulation.