Relationship between kinematics, F2 slope and speech intelligibility in dysarthria due to cerebral palsy

Articulatory and Vocal Fold Movement Patterns During Loud Speech in Children With Cerebral Palsy

PURPOSE

Speech motor control changes underlying louder speech are poorly understood in children with cerebral palsy (CP). The current study evaluates changes in the oral articulatory and laryngeal subsystems in children with CP and their typically developing (TD) peers during louder speech.

METHOD

Nine children with CP and nine age- and sex-matched TD peers produced sentence repetitions in two conditions: (a) with their habitual rate and loudness and (b) with louder speech. Lip and jaw movements were recorded with optical motion capture. Acoustic recordings were obtained to evaluate vocal fold articulation.

RESULTS

Children with CP had smaller jaw movements, larger lower lip movements, slower jaw speeds, faster lip speeds, reduced interarticulator coordination, reduced low-frequency spectral tilt, and lower cepstral peak prominences (CPP) in comparison to their TD peers. Both groups produced louder speech with larger lip and jaw movements, faster lip and jaw speeds, increased temporal coordination, reduced movement variability, reduced spectral tilt, and increased CPP.

CONCLUSIONS

Children with CP differ from their TD peers in the speech motor control of both the oral articulatory and laryngeal subsystems. Both groups alter oral articulatory and vocal fold movements when cued to speak loudly, which may contribute to the increased intelligibility associated with louder speech.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24970302.

Hierarchical Temporal Structuring of Speech: A Multiscale, Multimodal Framework to Inform the Assessment and Management of Neuromotor Speech Disorder

PURPOSE

Hierarchical temporal structuring of speech is the key to multiscale linguistic information transfer toward effective communication. This study investigated and linked the hierarchical temporal cues of the kinematic and acoustic modalities of natural, unscripted speech in neurologically healthy and impaired speakers.

METHOD

Thirteen individuals with amyotrophic lateral sclerosis (ALS) and 10 age-matched healthy controls performed a story-telling task. The hierarchical temporal structure of the speech stimulus was measured by (a) 26 articulatory-kinematic features characterizing the depth, phase synchronization, and coherence of temporal modulation of the tongue tip, tongue body, lower lip, and jaw, at three hierarchically nested timescales corresponding to prosodic stress, syllables, and onset-rime/phonemes, and (b) 25 acoustic features characterizing the parallel aspects of temporal modulation of five critical-spectral-band envelopes. All features were compared between groups. For each aspect of temporal modulation, the contributions of all articulatory features to the parallel acoustic features were evaluated by group.

RESULTS

Generally consistent disease impacts were identified on the articulatory and acoustic features, manifested by reduced modulation depths of most articulators and critical-spectral-band envelopes, primarily at the timescales of syllables and onset-rime/phonemes. For healthy speakers, the strongest articulatory-acoustic relationships were found for (a) jaw and lip, in modulating stress timing, and (b) tongue tip, in modulating the timing relation between onset-rime/phonemes and syllables. For speakers with ALS, the tongue body, tongue tip, and jaw all showed the greatest contributions to modulating syllable timing.

CONCLUSIONS

The observed disease impacts likely reflect reduced entrainment of speech motor activities to finer-grained linguistic events, presumably due to the dynamic constraints of the neuromuscular system. To accommodate these restrictions, speakers with ALS appear to use their residual articulatory motor capacities to accentuate and convey the perceptually most salient temporal cues underpinned by the syllable-centric parsing mechanism. This adaptive strategy has potential implications in managing neuromotor speech disorders.

Neuromuscular adaptations of swallowing and speech in unilateral cerebral palsy: shared and distinctive traits

Our aims were to 1) examine the neuromuscular control of swallowing and speech in children with unilateral cerebral palsy (UCP) compared with typically developing children (TDC), 2) determine shared and separate neuromuscular underpinnings of the two functions, and 3) explore the relationship between this control and behavioral outcomes in UCP. Surface electromyography (sEMG) was used to record muscle activity from the submental and superior and inferior orbicularis oris muscles during standardized swallowing and speech tasks. The variables examined were normalized mean amplitude, time to peak amplitude, and bilateral synchrony. Swallowing and speech were evaluated using standard clinical measures. Sixteen children with UCP and 16 TDC participated (7-12 yr). Children with UCP demonstrated higher normalized mean amplitude and longer time to peak amplitude across tasks than TDC (P < 0.01; and P < 0.02) and decreased bilateral synchrony than TDC for swallows (P < 0.01). Both shared and distinctive neuromuscular patterns were observed between swallowing and speech. In UCP, higher upper lip amplitude during swallows was associated with shorter normalized mealtime durations, whereas higher submental bilateral synchrony was related to longer mealtime durations. Children with UCP demonstrate neuromuscular adaptations for swallowing and speech, which should be further evaluated for potential treatment targets. Furthermore, both shared and distinctive neuromuscular underpinnings between the two functions are documented.NEW & NOTEWORTHY Systematically studying the swallowing and speech of children with UCP is new and noteworthy. We found that they demonstrate neuromuscular adaptations for swallowing and speech compared with typically developing peers. We examined swallowing and speech using carefully designed tasks, similar in motor complexity, which allowed us to directly compare patterns. We found shared and distinctive neuromuscular patterns between swallowing and speech.

Effects of Speaking Rate on Variability of Second Formant Frequency Transitions in Dysarthria

INTRODUCTION

This study examined the utility of multiple second formant (F2) slope metrics to capture differences in speech production for individuals with dysarthria and healthy controls as a function of speaking rate. In addition, the utility of F2 slope metrics for predicting severity of intelligibility impairment in dysarthria was examined.

METHODS

Twenty three speakers with Parkinson's disease and mild to moderate hypokinetic dysarthria (HD), 9 speakers with various neurological diseases and mild to severe ataxic or ataxic-spastic dysarthria (AD), and 26 age-matched healthy control speakers (CON) participated in a sentence repetition task. Sentences were produced at habitual, fast, and slow speaking rate. A variety of metrics were derived from the rising F2 transition portion of the diphthong /ai/. To obtain measures of intelligibility for the two clinical speaker groups, 15 undergraduate SLP students participated in a transcription experiment.

RESULTS

Significantly shallower slopes were found for the speakers with HD compared to control speakers. Steeper F2 slopes were associated with increased speaking rate for all groups. Higher variability in F2 slope metrics was found for the speakers with AD compared to the two other speaker groups. For both clinical speaker groups, there was a negative association between intelligibility and F2 slope variability metrics, indicating lower variability in speech production was associated with higher intelligibility.

DISCUSSION

F2 slope metrics were sensitive to dysarthria presence, dysarthria type, and speaking rate. The current study provided evidence that the use of F2 slope variability measures has additional value to F2 slope averaged measures for predicting severity of intelligibility impairment in dysarthria.

3D Video Tracking Technology in the Assessment of Orofacial Impairments in Neurological Disease: Clinical Validation

PURPOSE

This study sought to determine whether clinically interpretable kinematic features extracted automatically from three-dimensional (3D) videos were correlated with corresponding perceptual clinical orofacial ratings in individuals with orofacial impairments due to neurological disorders.

METHOD

45 participants (19 diagnosed with motor neuron diseases [MNDs] and 26 poststroke) performed two nonspeech tasks (mouth opening and lip spreading) and one speech task (repetition of a sentence "Buy Bobby a Puppy") while being video-recorded in a standardized lab setting. The color video recordings of participants were assessed by an expert clinician-a speech language pathologist-on the severity of three orofacial measures: symmetry, range of motion (ROM), and speed. Clinically interpretable 3D kinematic features, linked to symmetry, ROM, and speed, were automatically extracted from video recordings, using a deep facial landmark detection and tracking algorithm for each of the three tasks. Spearman correlations were used to identify features that were significantly correlated (p value < .05) with their corresponding clinical scores. Clinically significant kinematic features were then used in the subsequent multivariate regression models to predict the overall orofacial impairment severity score.

RESULTS

Several kinematic features extracted from 3D video recordings were associated with their corresponding perceptual clinical scores, indicating clinical validity of these automatically derived measures. Different patterns of significant features were observed between MND and poststroke groups; these differences were aligned with clinical expectations in both cases.

CONCLUSIONS

The results show that kinematic features extracted automatically from simple clinical tasks can capture characteristics used by clinicians during assessments. These findings support the clinical validity of video-based automatic extraction of kinematic features.

A Probe Study on Vocal Development in Two Infants at Risk for Cerebral Palsy

The present work examined canonical babbling ratios longitudinally as a measure of onset and consolidation of canonical babbling in two infants at risk of cerebral palsy (CP) between 5 and 16 months. Ten typically developing infants were included for comparison at 6, 9, 12, and 16-19 months. Canonical babbling ratios (CBRs) were calculated from 5-min segments, and follow-up diagnostic outcomes were collected between 24 and 33 months. The two infants at risk demonstrated low CBR growth trajectories compared to the typical infant group, and slightly different patterns of consolidation. The two infants at risk were later diagnosed with different levels of CP and speech impairment severity. All infants demonstrated greater variability than expected. Studying canonical babbling and other prelinguistic milestones in this population may inform our perspective of the involvement of the motor system in the vocal domain. Additional implications on the analysis of canonical babbling using all-day home recordings are discussed.

Acoustic and Kinematic Assessment of Motor Speech Impairment in Patients With Suspected Four-Repeat Tauopathies

PURPOSE

The aim of this study was to use acoustic and kinematic speech measures to characterize type of motor speech impairment-apraxia of speech (AOS) versus dysarthria-in individuals with four-repeat tauopathy (4RT)-associated syndromes, including nonfluent variant primary progressive aphasia (nfvPPA), primary progressive AOS (PPAOS), corticobasal syndrome (CBS), and progressive supranuclear palsy syndrome (PSPs).

METHOD

Twenty patient participants were recruited and stratified into two groups: (a) a motor-speech-impaired group of individuals with nfvPPA, PPAOS, CBS, or PSPs and suspected 4RT pathology ("MSI+") and (b) a non-motor-speech-impaired group of individuals with logopenic variant primary progressive aphasia ("MSI-"). Ten healthy, age-matched controls also participated in the study. Participants completed a battery of speech tasks, and 15 acoustic and kinematic speech measures were derived. Quantitative speech measures were grouped into feature categories ("AOS features," "dysarthria features," "shared features"). In addition to quantitative speech measures, two certified speech-language pathologists made independent, blinded auditory-perceptual ratings of motor speech impairment. A principal component analysis (PCA) was conducted to investigate the relative contributions of quantitative features.

RESULTS

Quantitative speech measures were generally concordant with independent clinician ratings of motor speech impairment severity. Hypothesis-driven groupings of quantitative measures differentiated predominantly apraxic from predominantly dysarthric presentations within the MSI+ group. PCA results provided additional evidence for differential profiles of motor speech impairment in the MSI+ group; heterogeneity across individuals is explained in large part by varying levels of overall severity-captured by the shared feature variable group-and degree of apraxia severity, as measured by the AOS feature variable group.

CONCLUSIONS

Quantitative features reveal heterogeneity of MSI in the 4RT group in terms of both overall severity and subtype of MSI. Results suggest the potential for acoustic and kinematic speech assessment methods to inform characterization of motor speech impairment in 4RT-associated syndromes.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21401778.

Relationship between rate-elicited changes in muscular-kinematic control strategies and acoustic performance in individuals with ALS-A multimodal investigation

INTRODUCTION

As a key control variable, duration has been long suspected to mediate the organization of speech motor control strategies, which has management implications for neuromotor speech disorders. This study aimed to experimentally delineate the role of duration in organizing speech motor control in neurologically healthy and impaired speakers using a voluntary speaking rate manipulation paradigm.

METHODS

Thirteen individuals with amyotrophic lateral sclerosis (ALS) and 10 healthy controls performed a sentence reading task three times, first at their habitual rate, then at a slower rate. A multimodal approach combining surface electromyography, kinematic, and acoustic technologies was used to record jaw muscle activities, jaw kinematics, and speech acoustics. Six muscular-kinematic features were extracted and factor-analyzed to characterize the organization of the mandibular control hierarchy. Five acoustic features were extracted, measuring the spectrotemporal properties of the diphthong /ɑɪ/ and the plosives /t/ and /k/.

RESULTS

The muscular-kinematic features converged into two interpretable latent factors, reflecting the level and cohesiveness/flexibility of mandibular control, respectively. Voluntary rate reduction led to a trend toward (1) finer, less cohesive, and more flexible mandibular control, and (2) increased range and decreased transition slope of the diphthong formants, across neurologically healthy and impaired groups. Differential correlations were found between the rate-elicited changes in mandibular control and acoustic performance for neurologically healthy and impaired speakers.

CONCLUSIONS

The results provided empirical evidence for the long-suspected but previously unsubstantiated role of duration in (re)organizing speech motor control strategies. The rate-elicited reorganization of muscular-kinematic control contributed to the acoustic performance of healthy speakers, in ways consistent with theoretical predictions. Such contributions were less consistent in impaired speakers, implying the complex nature of speaking rate reduction in ALS, possibly reflecting an interplay of disease-related constraints and volitional duration control. This information may help to stratify and identify candidates for the rate manipulation therapy.

Acoustic Change Over Time in Spastic and/or Flaccid Dysarthria in Motor Neuron Diseases

PURPOSE

This study aims to investigate acoustic change over time as biomarkers to differentiate among spastic-flaccid dysarthria associated with amyotrophic lateral sclerosis (ALS), spastic dysarthria associated with primary lateral sclerosis (PLS), flaccid dysarthria associated with spinal and bulbar muscular atrophy (SBMA), and to explore how these acoustic parameters are affected by dysarthria severity.

METHOD

Thirty-three ALS patients with mixed flaccid-spastic dysarthria, 17 PLS patients with pure spastic dysarthria, 18 SBMA patients with pure flaccid dysarthria, and 70 controls, all French speakers, were included in the study. Speakers produced vowel-glide sequences targeting different vocal tract shape changes. The mean and coefficient of variation of the total squared change of mel frequency cepstral coefficients were used to capture the degree and variability of acoustic changes linked to vocal tract modifications over time. Differences in duration of acoustic events were also measured.

RESULTS

All pathological groups showed significantly less acoustic change compared to controls, reflecting less acoustic contrast in sequences. Spastic and mixed spastic-flaccid dysarthric speakers showed smaller acoustic changes and slower sequence production compared to flaccid dysarthria. For dysarthria subtypes associated with a spastic component, reduced degree of acoustic change was also associated with dysarthria severity.

CONCLUSIONS

The acoustic parameters partially differentiated among the dysarthria subtypes in relation to motor neuron diseases. While similar acoustic patterns were found in spastic-flaccid and spastic dysarthria, crucial differences were found between these two subtypes relating to variability. The acoustic patterns were much more variable in ALS. This method forms a promising clinical tool as a diagnostic marker of articulatory impairment, even at mild stage of dysarthria progression in all subtypes.

Relationships between maximum tongue pressure and second formant transition in speakers with different types of dysarthria

The effects of muscle weakness on speech are currently not fully known. We investigated the relationships between maximum tongue pressure and second formant transition in adults with different types of dysarthria. It focused on the slope in the second formant transition because it reflects the tongue velocity during articulation. Sixty-three Japanese speakers with dysarthria (median age, 68 years; interquartile range, 58–77 years; 44 men and 19 women) admitted to acute and convalescent hospitals were included. Thirty neurologically normal speakers aged 19–85 years (median age, 22 years; interquartile range, 21.0–23.8 years; 14 men and 16 women) were also included. The relationship between the maximum tongue pressure and speech function was evaluated using correlation analysis in the dysarthria group. Speech intelligibility, the oral diadochokinesis rate, and the second formant slope were based on the impaired speech index. More than half of the speakers had mild to moderate dysarthria. Speakers with dysarthria showed significantly lower maximum tongue pressure, speech intelligibility, oral diadochokinesis rate, and second formant slope than neurologically normal speakers. Only the second formant slope was significantly correlated with the maximum tongue pressure (r = 0.368, p = 0.003). The relationship between the second formant slope and maximum tongue pressure showed a similar correlation in the analysis of subgroups divided by sex. The oral diadochokinesis rate, which is related to the speed of articulation, is affected by voice on/off, mandibular opening/closing, and range of motion. In contrast, the second formant slope was less affected by these factors. These results suggest that the maximum isometric tongue strength is associated with tongue movement speed during articulation.

Speech intelligibility loss due to amyotrophic lateral sclerosis: the effect of tongue movement reduction on vowel and consonant acoustic features

The purpose of this study was to identify aspects of impaired tongue motor performance that limit the ability to produce distinct speech sounds and contribute to reduced speech intelligibility in individuals with dysarthria secondary to amyotrophic lateral sclerosis (ALS). We analyzed simultaneously recorded tongue kinematic and acoustic data from 22 subjects during three target words (cat, dog, and took). The subjects included 11 participants with ALS and 11 healthy controls from the X-ray microbeam dysarthria database (Westbury, 1994). Novel measures were derived based on the range and speed of relative movement between two quasi-independent regions of the tongue - blade and dorsum - to characterize the global pattern of tongue dynamics. These "whole tongue" measures, along with the range and speed of single tongue regions, were compared across words, groups (ALS vs. control), and measure types (whole tongue vs. tongue blade vs. tongue dorsum). Reduced range and speed of both global and regional tongue movements were found in participants with ALS relative to healthy controls, reflecting impaired tongue motor performance in ALS. The extent of impairment, however, varied across words and measure types. Compared with the regional tongue measures, the whole tongue measures showed more consistent disease-related changes across the target words and were more robust predictors of speech intelligibility. Furthermore, these whole tongue measures were correlated with various word-specific acoustic features associated with intelligibility decline in ALS, suggesting that impaired tongue movement likely contributes to reduced phonetic distinctiveness of both vowels and consonants that underlie speech intelligibility decline in ALS.

Effect of prosodic manipulation on articulatory kinematics and second formant trajectories in children

This study investigated effects of rate reduction and emphatic stress cues on second formant (F2) trajectories and articulatory movements during diphthong production in 11 typically developing school-aged children. F2 extent increased in slow and emphatic stress conditions, and tongue and jaw displacement increased in the emphatic stress condition compared to habitual speech. Tongue displacement significantly predicted F2 extent across speaking conditions. Results suggest that slow rate and emphatic stress cues induce articulatory and acoustic changes in children that may enhance clarity of the acoustic signal. Potential clinical implications for improving speech in children with dysarthria are discussed.

Predicting Speech Intelligibility Based on Spatial Tongue-Jaw Coupling in Persons With Amyotrophic Lateral Sclerosis: The Impact of Tongue Weakness and Jaw Adaptation

Purpose Motor neuron diseases, such as amyotrophic lateral sclerosis (ALS), have a devastating effect on speech muscle function that often results in severe communication deficits. Over the course of bulbar disease, tongue and jaw movements are modified, but their impact on speech is poorly understood. The aim of this study was to determine the effect of disease-related changes in tongue-jaw movement coupling on speech intelligibility in persons at different stages of bulbar ALS. Method Parallel factor analysis was used to quantify the pattern of spatial coupling between 4 semi-independent regions of the tongue and the jaw in various vowels and consonants in 10 individuals with ALS and 10 healthy individuals, respectively, from the X-Ray Microbeam database (Westbury, 1994). The relation of spatial tongue-jaw coupling to speech intelligibility was examined in individuals at the early and late stages of bulbar ALS and healthy individuals. Results Tongue movement, independent of the jaw, decreased early and progressively, which negatively impacted speech intelligibility. Jaw contribution to tongue movement was increased during the early stages of bulbar ALS compared to that of the healthy subjects, which was followed by a decrease during the late stages of bulbar ALS. The early-stage increase of jaw contribution significantly improved speech intelligibility and is thus most likely to be an adaptive strategy to mitigate the negative impact of tongue movement reductions on speech intelligibility. This adaptive strategy became unavailable during the late stages of bulbar ALS, which might accelerate intelligibility decline. Conclusions The loss of functional tongue-jaw coupling may be the critical physiological factor leading to the eventual loss of functional speech in ALS. Monitoring changes in tongue-jaw coupling may improve the prediction about the timing of speech loss and guide clinical management of dysarthria in ALS.

Relation of second formant trajectories to tongue kinematics

In this study, the relationship between the acoustic and articulatory kinematic domains of speech was examined among nine neurologically healthy female speakers using two derived relationships between tongue kinematics and F2 measurements: (1) second formant frequency (F2) extent to lingual displacement and (2) F2 slope to lingual speed. Additionally, the relationships between these paired parameters were examined within conversational, more clear, and less clear speaking modes. In general, the findings of the study support a strong correlation for both sets of paired parameters. In addition, the data showed significant changes in articulatory behaviors across speaking modes including the magnitude of tongue motion, but not in the speed-related measures.

Acoustic properties of vowel production in Mandarin-speaking patients with post-stroke dysarthria

This study investigated the acoustic features of vowel production in Mandarin-speaking patients with post-stroke dysarthria (PSD). The subjects included 31 native Mandarin-speaking patients with PSD (age: 25–83 years old) and 38 neurologically normal adults in a similar age range (age: 21–76 years old). Each subject was recorded producing a list of Mandarin monosyllables that included six monophthong vowels (i.e., /a, i, u, ɤ, y, o/) embedded in the /CV/ context. The patients’ speech samples were evaluated by two native Mandarin speakers. The evaluation scores were then used to classify all patients into two levels of severity: mild or moderate-to-severe. Formants (F1 and F2) were extracted from each vowel token. Results showed that all vowel categories in the patients with PSD were produced with more variability than in the healthy speakers. Great overlaps between vowel categories and reduced vowel space were observed in the patients. The magnitude of the vowel dispersion and overlap between vowel categories increased as a function of the severity of the disorder. The deviations of the vowel acoustic features in the patients in comparison to the healthy speakers may provide guidance for clinical rehabilitation to improve the speech intelligibility of patients with PSD.

Dysarthria in Mandarin-Speaking Children With Cerebral Palsy: Speech Subsystem Profiles

PURPOSE

This study explored the speech characteristics of Mandarin-speaking children with cerebral palsy (CP) and typically developing (TD) children to determine (a) how children in the 2 groups may differ in their speech patterns and (b) the variables correlated with speech intelligibility for words and sentences.

METHOD

Data from 6 children with CP and a clinical diagnosis of moderate dysarthria were compared with data from 9 TD children using a multiple speech subsystems approach. Acoustic and perceptual variables reflecting 3 speech subsystems (articulatory-phonetic, phonatory, and prosodic), and speech intelligibility, were measured based on speech samples obtained from the Test of Children's Speech Intelligibility in Mandarin (developed in the lab for the purpose of this research).

RESULTS

The CP and TD children differed in several aspects of speech subsystem function. Speech intelligibility scores in children with CP were influenced by all 3 speech subsystems, but articulatory-phonetic variables had the highest correlation with word intelligibility. All 3 subsystems influenced sentence intelligibility.

CONCLUSION

Children with CP demonstrated deficits in speech intelligibility and articulation compared with TD children. Better speech sound articulation influenced higher word intelligibility, but did not benefit sentence intelligibility.

Articulatory Kinematic Characteristics Across the Dysarthria Severity Spectrum in Individuals With Amyotrophic Lateral Sclerosis

PURPOSE

The current study investigated whether articulatory kinematic patterns can be extrapolated across the spectrum of dysarthria severity in individuals with amyotrophic lateral sclerosis (ALS).

METHOD

Temporal and spatial articulatory kinematic data were collected using electromagnetic articulography from 14 individuals with dysarthria secondary to ALS and 6 typically aging speakers. Speech intelligibility and speaking rate were used as indices of severity.

RESULTS

Temporal measures (duration, speed of articulators) were significantly correlated with both indices of severity. In speakers with dysarthria, spatial measures were not correlated with severity except in 3 measures: tongue movement displacement was more reduced in the anterior-posterior dimension; jaw movement distance was greater in the inferior-superior dimension; jaw convex hull area was larger in speakers with slower speaking rates. Visual inspection of movement trajectories revealed that overall spatial kinematic characteristics in speakers with severe dysarthria differed qualitatively from those in speakers with mild or moderate dysarthria. Unlike speakers with dysarthria, typically aging speakers displayed variable tongue movement and minimal jaw movement.

CONCLUSIONS

The current study revealed that spatial articulatory characteristics, unlike temporal characteristics, showed a complicated pattern across the severity spectrum. The findings suggest that articulatory characteristics in speakers with severe dysarthria cannot simply be extrapolated from those in speakers with mild-to-moderate dysarthria secondary to ALS.

Range and Precision of Formant Movement in Pediatric Dysarthria

PURPOSE

This study aimed to improve understanding of speech characteristics associated with dysarthria in children with cerebral palsy by analyzing segmental and global formant measures in single-word and sentence contexts.

METHOD

Ten 5-year-old children with cerebral palsy and dysarthria and 10 age-matched, typically developing children participated in this study. Vowel space area and second formant interquartile range were measured from children's elicited productions of single words and sentences.

RESULTS

Results showed that the children with dysarthria had significantly smaller vowel space areas than typically developing children in both word and sentence contexts; however, overall ranges of second formant movement did not differ between groups in word or sentence contexts. Additional analysis of single words revealed that, compared to typical children, children with dysarthria had smaller second formant interquartile ranges in single words with phonetic contexts requiring large changes in vocal tract configuration, but not in single words with monophthongs.

CONCLUSIONS

Results of this study suggest that children with dysarthria may not have globally reduced ranges of articulatory movement compared to typically developing peers; however, they do exhibit reduced precision in producing phonetic targets.

Initial Observations of Lingual Movement Characteristics of Children With Cerebral Palsy

PURPOSE

This preliminary study compared the speech motor control of the tongue and jaw between children with cerebral palsy (CP) and their typically developing (TD) peers.

METHOD

Tongue tip and jaw movements of 4 boys with spastic CP and 4 age- and sex-matched TD peers were recorded using an electromagnetic articulograph during 10 repetitions of "Dad told stories today." The duration, path distance, average speed, and speech movement stability of the movements were calculated for each repetition.

RESULTS

The children with CP had longer durations than their TD peers. Children with CP had longer path distances and faster average speed as compared with their TD peers for both articulators. The TD group but not the CP group had longer path distances and faster average speeds for the tongue than the jaw. The CP group had reduced speech movement stability for the tongue as compared with their TD peers, but both groups had similar speech movement stability for the jaw.

CONCLUSIONS

Children with CP had impaired speech motor control of the tongue and jaw as compared with their TD peers, and these speech motor control deficits were more pronounced in the tongue tip than the jaw.

Jaw Rotation in Dysarthria Measured With a Single Electromagnetic Articulography Sensor

PURPOSE

This study evaluated a novel method for characterizing jaw rotation using orientation data from a single electromagnetic articulography sensor. This method was optimized for clinical application, and a preliminary examination of clinical feasibility and value was undertaken.

METHOD

The computational adequacy of the single-sensor orientation method was evaluated through comparisons of jaw-rotation histories calculated from dual-sensor positional data for 16 typical talkers. The clinical feasibility and potential value of single-sensor jaw rotation were assessed through comparisons of 7 talkers with dysarthria and 19 typical talkers in connected speech.

RESULTS

The single-sensor orientation method allowed faster and safer participant preparation, required lower data-acquisition costs, and generated less high-frequency artifact than the dual-sensor positional approach. All talkers with dysarthria, regardless of severity, demonstrated jaw-rotation histories with more numerous changes in movement direction and reduced smoothness compared with typical talkers.

CONCLUSIONS

Results suggest that the single-sensor orientation method for calculating jaw rotation during speech is clinically feasible. Given the preliminary nature of this study and the small participant pool, the clinical value of such measures remains an open question. Further work must address the potential confound of reduced speaking rate on movement smoothness.

Acoustic and tongue kinematic vowel space in speakers with and without dysarthria

PURPOSE

The purpose is to investigate acoustic and tongue body kinematic vowel dispersion patterns and vowel space in speakers with and without dysarthria secondary to amyotrophic lateral sclerosis (ALS).

METHOD

Acoustic and tongue kinematic vowel spaces were examined at the same time sampling point using electromagnetic articulography in 11 speakers with dysarthria secondary to ALS and 11 speakers without dysarthria. Tongue kinematic data were collected from the tongue body sensor (∼25 mm posterior from the tongue apex). A number of acoustic and tongue body kinematic variables were tested.

RESULT

The result showed that the acoustic and tongue kinematic vowel dispersion patterns are different between the groups. Acoustic and tongue body kinematic vowel spaces are highly correlated; however, unlike acoustic vowel space, tongue body kinematic vowel space was not significantly different between the groups.

CONCLUSION

Both acoustic and tongue kinematic vowel dispersion patterns are sensitive to the group difference, especially with high vowels. The tongue kinematic vowel space approach is too crude to differentiate the speakers with dysarthria secondary to ALS from speakers without dysarthria. To examine tongue range of motion in speakers with dysarthria, a more refined articulatory kinematic approach needs to be examined in the future.

Interarticulator coordination in children with and without cerebral palsy

The current study investigates how interarticulator coordination changes across speaking tasks varying in articulatory and linguistic demands for children with CP and their typically-developing peers. Articulatory movements from 12 children with spastic CP (7M, 5F, 4-15 years of age) and 12 typically-developing age- and sex-matched peers were cross-correlated to determine the degree of spatial and temporal coupling between the upper lip and jaw, lower lip and jaw, and upper and lower lips. Spatial and temporal coupling were also correlated with intelligibility. Results indicated that children with CP have reduced spatial coupling between the upper and lower lips and reduced temporal coupling between all articulators as compared to their typically-developing peers. For all participants, sentences were produced with the greatest degree of interarticulator coordination when compared to the diadochokinetic and syllable repetition tasks. Measures of interarticulator coordination were correlated with intelligibility for the speakers with CP.

A Modeling Study of the Effects of Vocal Tract Movement Duration and Magnitude on the F2 Trajectory in CV Words

PURPOSE

This study used a computational vocal tract model to investigate the relationship of diphthong duration and vocal tract movement magnitude to measures of the F2 trajectory in CV words.

METHOD

Three words (bough, boy, and buy) were simulated on the basis of an adult female vocal tract model, in which the model parameters were estimated from audio recordings of a female talker. Model parameters were then modified to generate 35 simulations of each word corresponding to 7 different durations and 5 movement magnitude settings. In addition, these simulations were repeated with vocal tract lengths representative of an adult male and an approximately 6-year-old child.

RESULTS

On the basis of univariate analysis, measures of frequency predicted changes in magnitude, and temporal measures predicted changes in speaking rate consistent with the hypothesis. The combined effects of duration and magnitude showed that F2 was more sensitive to changes in magnitude at shorter word durations compared with longer word durations. This finding held across words and vocal tract length.

CONCLUSIONS

Results suggest that there is an interaction between duration and magnitude that affects the slope of the F2 trajectory. The next step is to relate kinematics to F2 trajectory output using real speakers.

Dysarthria in Adults With Cerebral Palsy: Clinical Presentation and Impacts on Communication

PURPOSE

Although dysarthria affects the large majority of individuals with cerebral palsy (CP) and can substantially complicate everyday communication, previous research has provided an incomplete picture of its clinical features. We aimed to comprehensively describe characteristics of dysarthria in adults with CP and to elucidate the impact of dysarthric symptoms on parameters relevant for communication.

METHOD

Forty-two adults with CP underwent speech assessment by means of standardized auditory rating scales. Listening experiments were conducted to obtain communication-related parameters-that is, intelligibility and naturalness-as well as age and gender estimates.

RESULTS

The majority of adults with CP showed moderate to severe dysarthria with symptoms on all dimensions of speech, most prominently voice quality, respiration, and prosody. Regression analyses revealed that articulatory, respiratory, and prosodic features were the strongest predictors of intelligibility and naturalness of speech. Listeners' estimates of the speakers' age and gender were predominantly determined by voice parameters.

CONCLUSION

This study provides an overview on the clinical presentation of dysarthria in a convenience sample of adults with CP. The complexity of the functional impairment described and the consequences on the individuals' communication call for a stronger consideration of dysarthria in CP both in clinical care and in research.

Variability and Diagnostic Accuracy of Speech Intelligibility Scores in Children

PURPOSE

We examined variability of speech intelligibility scores and how well intelligibility scores predicted group membership among 5-year-old children with speech motor impairment (SMI) secondary to cerebral palsy and an age-matched group of typically developing (TD) children.

METHOD

Speech samples varying in length from 1-4 words were elicited from 24 children with cerebral palsy (mean age 60.50 months) and 20 TD children (mean age 60.33 months). Two hundred twenty adult listeners made orthographic transcriptions of speech samples (n = 5 per child).

RESULTS

Variability associated with listeners made a significant contribution to explaining the variance in intelligibility scores for TD and SMI children, but the magnitude was greater for TD children. Intelligibility scores differentiated very well between children who have SMI and TD children when intelligibility was at or below approximately 75% and above approximately 85%.

CONCLUSIONS

Intelligibility seems to be a useful clinical tool for differentiating between TD children and children with SMI at 5 years of age; however, there is considerable variability within and between listeners, highlighting the need for more than one listener per child to ensure validity of an intelligibility measure.

Predicting speech intelligibility with a multiple speech subsystems approach in children with cerebral palsy

PURPOSE

Speech acoustic characteristics of children with cerebral palsy (CP) were examined with a multiple speech subsystems approach; speech intelligibility was evaluated using a prediction model in which acoustic measures were selected to represent three speech subsystems.

METHOD

Nine acoustic variables reflecting different subsystems, and speech intelligibility, were measured in 22 children with CP. These children included 13 with a clinical diagnosis of dysarthria (speech motor impairment [SMI] group) and 9 judged to be free of dysarthria (no SMI [NSMI] group). Data from children with CP were compared to data from age-matched typically developing children.

RESULTS

Multiple acoustic variables reflecting the articulatory subsystem were different in the SMI group, compared to the NSMI and typically developing groups. A significant speech intelligibility prediction model was obtained with all variables entered into the model (adjusted R2 = .801). The articulatory subsystem showed the most substantial independent contribution (58%) to speech intelligibility. Incremental R2 analyses revealed that any single variable explained less than 9% of speech intelligibility variability.

CONCLUSIONS

Children in the SMI group had articulatory subsystem problems as indexed by acoustic measures. As in the adult literature, the articulatory subsystem makes the primary contribution to speech intelligibility variance in dysarthria, with minimal or no contribution from other systems.

Rate-related kinematic changes in younger and older adults

AIMS

This study aimed to investigate the effects of speech rate changes on kinematic characteristics and stability of speech movements in younger and older speakers using electromagnetic midsagittal articulography.

PATIENTS AND METHODS

Eight young adults and 8 older adults engaged in a series of syllable repetition tasks of /pa/, /sa/ and /ta/ obtained at self-paced slow, habitual and fast speech rates, as well as in a series of metronome-guided speech rates, ranging from 2 to 4 syllables per second. The kinematic parameters duration, amplitude and peak velocity were obtained for opening and closing movements.

RESULTS

Older speakers were able to increase speech rate to the same degree or higher compared to younger speakers in both pacing conditions. Kinematic data show that older adults increased duration and decreased peak velocity in closing movements of alveolar constrictions at slower rates more prominently than younger adults. The results on movement stability revealed no differences between age groups.

CONCLUSIONS

The results suggest that an age-related difference in speed-accuracy trade-off can be ruled out. Differences in kinematic characteristics point towards the possibility that older adults aimed to facilitate a closed-loop control system to maintain movement stability at slower speech rates.