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

Chronic respiratory failure negatively affects speech function in patients with bulbar and spinal onset amyotrophic lateral sclerosis: retrospective data from a tertiary referral center

Background: Although dysarthria and respiratory failure are widely described in literature as part of the natural history of Amyotrophic lateral sclerosis (ALS), the specific interaction between them has been little explored.Aim: To investigate the relationship between chronic respiratory failure and the speech of ALS patients.Materials and methods: In this cross-sectional retrospective study we reviewed the medical records of all patients diagnosed with ALS that were accompanied by a tertiary referral center. In order to determine the presence and degree of speech impairment, the Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRS-R) speech sub-scale was used. Respiratory function was assessed through spirometry and through venous blood gasometry obtained from a morning peripheral venous sample. To determine whether differences among groups classified by speech function were significant, maximum and mean spirometry values of participants were compared using multivariate analysis of variance (MANOVA) with Tukey's post hoc test.Results: Seventy-five cases were selected, of which 73.3% presented speech impairment and 70.7% respiratory impairment. Respiratory and speech functions were moderately correlated (seated FVC r = 0.64; supine FVC r = 0.60; seated FEV1 r = 0.59 and supine FEV1 r = 0.54, p < .001). Multivariable logistic regression revealed that the following variables were significantly associated with the presence of speech impairment after adjusting for other risk factors: seated FVC (odds ratio [OR] = 0.862) and seated FEV1 (OR = 1.106). The final model was 81.1% predictive of speech impairment. The presence of daytime hypercapnia was not correlated to increasing speech impairment.Conclusion: The restrictive pattern developed by ALS patients negatively influences speech function. Speech is a complex and multifactorial process, and lung volume presents a pivotal role in its function. Thus, we were able to find that lung volumes presented a significant correlation to speech function, especially in those with bulbar onset and respiratory impairment. Neurobiological and physiological aspects of this relationship should be explored in further studies with the ALS population.

Comparison of Vowel and Sentence Intelligibility in People With Dysarthria Secondary to Amyotrophic Lateral Sclerosis

PURPOSE

In this study, we examined the utility of vowel intelligibility testing for assessing the impact of dysarthria on speech characteristics in people with amyotrophic lateral sclerosis (ALS). We tested the sensitivity and specificity of overall vowel identification, as well as that of vowel-specific identification, to dysarthria presence and severity. We additionally examined the relationship between vowel intelligibility and sentence intelligibility.

METHOD

Twenty-three people with ALS and 22 age- and sex-matched control speakers produced sentences from the Speech Intelligibility Test (SIT), as well as 10 American English monophthongs in /h/-vowel-/d/ words for the vowel intelligibility test (VIT). Data for SIT and VIT scores came from 135 listeners. Diagnostic accuracy of VIT measures was evaluated using the area under the curve of receiver operator characteristics. We then examined differences between control speakers, speakers with mild dysarthria, and speakers with severe dysarthria in their relationship between SIT and VIT scores.

RESULTS

The results suggest that the overall vowel intelligibility score showed high sensitivity and specificity in differentiating between speakers with and without dysarthria, even those with milder symptoms. In addition, single-vowel identification scores showed at least acceptable group differentiation between the mild and severe dysarthria groups, though fewer single vowels were acceptable discriminators between the control group and the group with mild dysarthria. Identification accuracy of /ɪ/ in particular showed excellent discrimination across all groups. Examination of the relationship between SIT and VIT scores suggests a severity-specific relationship. Speakers with SIT scores above 70% generally had higher SIT than VIT scores, whereas speakers with SIT below 70% generally had higher VIT than SIT scores.

DISCUSSION

Vowel intelligibility testing can detect speech impairments in speakers with mild dysarthria and residual articulatory function in speakers with severe dysarthria. Vowel intelligibility testing may, therefore, be a useful addition to intelligibility testing for individuals with dysarthria.

Articulation distortion in Mandarin-speaking individuals with complete arch maxillary implant-supported fixed dental prostheses

STATEMENT OF PROBLEM

Implant-supported fixed dental prostheses (IFPs) have been increasingly used to restore edentulous jaws, yet few studies have utilized acoustic analysis for objective evaluation of postrestoration speech outcomes.

PURPOSE

The purpose of this clinical study was to assess speech articulation in edentulous individuals before and after the provision of IFPs by combining the results of subjective evaluations and objective acoustic analysis parameters.

MATERIAL AND METHODS

The study included thirty-four individuals who had an edentulous maxilla and had been provided with an IFP for over 6 months, along with 6 dentate controls. Acoustic analysis was conducted, and mean opinion scores (MOS) were rated from recordings. The participants were interviewed about perceived speech changes. Changes in the parameters were evaluated using the paired t test or Wilcoxon signed-rank test (α=.05). A comparison between dentate controls and edentulous individuals (with or without prostheses) was made using an independent t test or Mann-Whitney U test (α=.025).

RESULTS

Following restoration, the center of gravity (CoG) changes occurred in 11 of 12 consonants in edentulous individuals (P<.05). Prosthesis use allowed the CoG of all affricates and fricatives to appear larger and closer to control values. Before restoration, the CoG of 9 of 12 consonants in edentulous individuals differed from controls (P<.01); after restoration, this reduced to 3 out of 12 (P<.01). MOS improved in 10 of 12 consonants (P<.01), nearing a score of 4. Despite restoration, the CoG of alveolo-palatals [tɕh], [tɕ], and [ɕ] remained different from controls (P<.01). Most participants were satisfied with the improvement, with few reporting discomfort with alveolars [s] and [tsh].

CONCLUSIONS

IFPs can enhance speech in edentulous individuals, yet articulation distortions of alveolar and alveolo-palatal consonants persist. The improper palatal shape of IFPs or an abrupt joint between the IFP and atrophic natural bone may contribute to these distortions.

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.

Video-Based Facial Movement Analysis in the Assessment of Bulbar Amyotrophic Lateral Sclerosis: Clinical Validation

PURPOSE

Facial movement analysis during facial gestures and speech provides clinically useful information for assessing bulbar amyotrophic lateral sclerosis (ALS). However, current kinematic methods have limited clinical application due to the equipment costs. Recent advancements in consumer-grade hardware and machine/deep learning made it possible to estimate facial movements from videos. This study aimed to establish the clinical validity of a video-based facial analysis for disease staging classification and estimation of clinical scores.

METHOD

Fifteen individuals with ALS and 11 controls participated in this study. Participants with ALS were stratified into early and late bulbar ALS groups based on their speaking rate. Participants were recorded with a three-dimensional (3D) camera (color + depth) while repeating a simple sentence 10 times. The lips and jaw movements were estimated, and features related to sentence duration and facial movements were used to train a machine learning model for multiclass classification and to predict the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) bulbar subscore and speaking rate.

RESULTS

The classification model successfully separated healthy controls, the early ALS group, and the late ALS group with an overall accuracy of 96.1%. Video-based features demonstrated a high ability to estimate the speaking rate (adjusted R ² = .82) and a moderate ability to predict the ALSFRS-R bulbar subscore (adjusted R ² = .55).

CONCLUSIONS

The proposed approach based on a 3D camera and machine learning algorithms represents an easy-to-use and inexpensive system that can be included as part of a clinical assessment of bulbar ALS to integrate facial movement analysis with other clinical data seamlessly.

Articulatory Underpinnings of Reduced Acoustic-Phonetic Contrasts in Individuals With Amyotrophic Lateral Sclerosis

PURPOSE

The aim of this study is to identify the articulatory underpinnings of the acoustic-phonetic correlates of functional speech decline in individuals with amyotrophic lateral sclerosis (ALS).

METHOD

Thirteen individuals with varying severities of speech impairment secondary to ALS and 10 neurologically healthy controls speakers read 12 minimal word pairs, targeting the contrasts in the height, advancement, and length of vowels; the manner and place of articulation for consonants and consonant cluster; and liquid and glide approximants, 5 times. Sixteen acoustic features were extracted to characterize the phonetic contrasts of these minimal word pairs. These acoustic features were correlated with a functional speech index-intelligible speaking rate-using penalized regression, based on which the contributive features were identified as the acoustic-phonetic correlates of the functional speech outcome. Articulatory contrasts of the minimal word pairs were characterized by a set of dissimilarity indices derived by the dynamic time warping algorithm, which measured the differences in the displacement and velocity trajectories of tongue tip, tongue dorsum, lower lip, and jaw between the minimal word pairs. The contributive articulatory features to the acoustic-phonetic correlates were identified by penalized regression.

RESULTS

A variety of acoustic-phonetic features were identified as contributing to the functional speech outcome, of which the contrasts in vowel height and advancement, [r]-[l], [r]-[w], and initial cluster-singleton were the most affected in individuals with ALS. Differential articulatory underpinnings were identified for these acoustic-phonetic features. Impairments of these articulatory underpinnings, especially of tongue tip and tongue dorsum velocities and tongue tip displacement, were associated with reduced acoustic-phonetic contrasts of the minimal word pairs, in a context-specific manner.

CONCLUSION

The findings established explanatory relationships between articulatory impairment and the acoustic-phonetic profile of functional speech decline in ALS, providing useful information for developing targeted management strategies to improve and prolong functional speech in individuals with ALS.

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.

"You Say Severe, I Say Mild": Toward an Empirical Classification of Dysarthria Severity

PURPOSE

The main purpose of this study was to create an empirical classification system for speech severity in patients with dysarthria secondary to amyotrophic lateral sclerosis (ALS) by exploring the reliability and validity of speech-language pathologists' (SLPs') ratings of dysarthric speech.

METHOD

Ten SLPs listened to speech samples from 52 speakers with ALS and 20 healthy control speakers. SLPs were asked to rate the speech severity of the speakers using five response options: normal, mild, moderate, severe, and profound. Four severity-surrogate measures were also calculated: SLPs transcribed the speech samples for the calculation of speech intelligibility and rated the effort it took to understand the speakers on a visual analog scale. In addition, speaking rate and intelligible speaking rate were calculated for each speaker. Intrarater and interrater reliability were calculated for each measure. We explored the validity of clinician-based severity ratings by comparing them to the severity-surrogate measures. Receiver operating characteristic (ROC) curves were conducted to create optimal cutoff points for defining dysarthria severity categories.

RESULTS

Intrarater and interrater reliability for the clinician-based severity ratings were excellent and were comparable to reliability for the severity-surrogate measures explored. Clinician severity ratings were strongly associated with all severity-surrogate measures, suggesting strong construct validity. We also provided a range of values for each severity-surrogate measure within each severity category based on the cutoff points obtained from the ROC analyses.

CONCLUSIONS

Clinician severity ratings of dysarthric speech are reliable and valid. We discuss the underlying challenges that arise when selecting a stratification measure and offer recommendations for a classification scheme when stratifying patients and research participants into speech severity categories.

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.

Assessment of dysarthria and dysphagia in patients with amyotrophic lateral sclerosis: Review of the current evidence

Bulbar dysfunction is a common presentation of amyotrophic lateral sclerosis (ALS) and significantly impacts quality of life of people with ALS (PALS). The current paper reviews measurements of dysarthria and dysphagia specific to ALS to identify efficient and valid assessment measures. Using such assessment measures will lead to improved management of bulbar dysfunction in ALS. Measures reviewed for dysarthria in PALS are organized into three categories: acoustic, kinematic, and strength. A set of criteria are used to evaluate the effectiveness of the measures' identification of speech impairments, measurement of functional verbal communication, and clinical applicability. Assessments reviewed for dysphagia in PALS are organized into six categories: patient reported outcomes, dietary intake, pulmonary function and airway defense capacity, bulbar function, dysphagia/aspiration screens, and instrumental evaluations. Measurements that have good potential for clinical use are highlighted in both topic areas. Additionally, areas of improvement for clinical practice and research are identified and discussed. In general, no single speech measure fulfilled all the criteria, although a few measures were identified as potential diagnostic tools. Similarly, few objective measures that were validated and replicated with large sample sizes were found for diagnosis of dysphagia in PALS. Importantly, clinical applicability was found to be limited; thus, a collaborative team focused on implementation science would be helpful to improve the clinical uptake of assessments. Overall, the review highlights the need for further development of clinically viable and efficient measurements that use a multidisciplinary approach.

Validation of Articulatory Rate and Imprecision Judgments in Speech of Individuals With Amyotrophic Lateral Sclerosis

Purpose Perceptual judgments of articulatory function are commonly used by speech-language pathologists to evaluate articulatory performance in individuals with amyotrophic lateral sclerosis (ALS). The goal of this study was to evaluate the psychometric properties (e.g., reliability, validity) of these perceptual measures to inform their application as part of a comprehensive bulbar assessment tool in ALS. Method Preexisting data from 51 individuals with ALS were obtained from a larger longitudinal study. Five independent raters provided perceptual judgments of articulatory rate and imprecision in a sentence task. Inter- and intrarater reliability of these judgments were assessed. Perceptual ratings were correlated with an acoustic measure of articulatory rate, in syllables per second, obtained from passage-reading recordings. Both perceptual and acoustic measures were correlated with gold-standard kinematic tongue and jaw movement measures, recorded from sentences using electromagnetic articulography. Results The results revealed good inter- and intrarater reliability of perceptual judgments of articulatory function. Strong correlations were observed between perceptual ratings of articulatory rate and imprecision and acoustic measures of articulatory rate and kinematic measures of tongue speed. Conclusions These findings support the clinical application of perceptual judgments of articulatory function as valid and reliable measures of underlying articulatory changes in bulbar ALS. Additional research is needed to understand the responsiveness of these measures to clinical changes in articulatory function in ALS.

Neuromotor Speech Recovery Across Different Behavioral Speech Modifications in Individuals Following Facial Transplantation

Despite signs of facial nerve recovery within a few months following face transplantation, speech deficits persist for years. Behavioral speech modifications (e.g., slower-than-normal speaking rate and increased loudness) have shown promising potential to enhance speech intelligibility in populations with dysarthric speech. However, such evidence-based practice approach is lacking in clinical management of speech in individuals with facial transplantation. Because facial transplantation involves complex craniofacial reconstruction and facial nerve coaptation, it is unknown to what extent individuals with face transplant are capable of adapting their motor system to task-specific articulatory demands. The purpose of this study was to identify the underlying articulatory mechanisms employed by individuals with face transplantation in response to speech modification cues at early and late stages of neuromotor recovery. In addition, we aimed to identify speech modifications that conferred improved speech clarity. Participants were seven individuals who underwent full or partial facial vascularized composite allografts that included lips and muscles of facial animation and were in early (~2 months) or late (~42 months) stages of recovery. Participants produced repetitions of the sentence “Buy Bobby a puppy” in normal, fast, loud, and slow speech modifications. Articulatory movement traces were recorded using a 3D optical motion capture system. Kinematic measures of average speed (mm/s) and range of movement (mm³) were extracted from the lower lip (± jaw) marker. Two speech language pathologists rated speech clarity for each speaker using a visual analog scale (VAS) approach. Results demonstrated that facial motor capacity increased from early to late stages of recovery. While individuals in the early group exhibited restricted capabilities to adjust their motor system based on the articulatory demands of each speech modification, individuals in the late group demonstrated faster speed and larger-than-normal range of movement for loud speech, and slower speed and larger-than-normal range of movement for slow speech. In addition, subjects in both groups showed overreliance on jaw rather than lip articulatory function across all speech modifications, perhaps as a compensatory strategy to optimize articulatory stability and maximize speech function. Finally, improved speech clarity was associated with loud speech in both stages of recovery.

Patterns of Misidentified Vowels in Individuals With Dysarthria Secondary to Amyotrophic Lateral Sclerosis

Purpose The current study examines the pattern of misidentified vowels produced by individuals with dysarthria secondary to amyotrophic lateral sclerosis (ALS). Method Twenty-three individuals with ALS and 22 typical individuals produced 10 monophthongs in an /h/-vowel-/d/ context. One hundred thirty-five listeners completed a forced-choice vowel identification test. Misidentified vowels were examined in terms of the target vowel categories (front-back; low-mid-high) and the direction of misidentification (the directional pattern when the target vowel was misidentified, e.g., misidentification "to a lower vowel"). In addition, acoustic predictors of vowel misidentifications were tested based on log first formant (F1), log second formant, log F1 vowel inherent spectral change, log second formant vowel inherent spectral change, and vowel duration. Results First, high and mid vowels were more frequently misidentified than low vowels for all speaker groups. Second, front and back vowels were misidentified at a similar rate for both the Mild and Severe groups, whereas back vowels were more frequently misidentified than front vowels in typical individuals. Regarding the direction of vowel misidentification, vowel errors were mostly made within the same backness (front-back) category for all groups. In addition, more errors were found toward a lower vowel category than toward a higher vowel category in the Severe group, but not in the Mild group. Overall, log F1 difference was identified as a consistent acoustic predictor of the main vowel misidentification pattern. Conclusion Frequent misidentifications in the vowel height dimension and the acoustic predictor, F1, suggest that limited tongue height control is the major articulatory dysfunction in individuals with ALS. Clinical implications regarding this finding are discussed.

Direction-Specific Jaw Dysfunction and Its Impact on Tongue Movement in Individuals With Dysarthria Secondary to Amyotrophic Lateral Sclerosis

Purpose The current study tested jaw movement characteristics and their impact on tongue movement for speech production in individuals with amyotrophic lateral sclerosis (ALS). Specifically, the study examined tongue and jaw movement in multiple directions during jaw opening and closing strokes in individuals with ALS and controls. Method Twenty-two individuals with ALS and 22 controls participated in the current study. Tongue and jaw movements during the production of the words "Iowa" and "Ohio" (produced in a carrier phrase) were recorded using electromagnetic articulography. Tongue and jaw distances were measured for jaw opening and closing strokes. Distance was measured in the anterior-posterior and superior-inferior dimensions (retraction, advancement, lowering, and raising). Results Findings revealed that individuals with ALS exaggerated their jaw opening movements, but not their jaw closing movements, compared to controls. Between the groups, a comparable tongue lowering distance was observed during jaw opening movements. In contrast, reduced tongue raising was observed during the jaw closing movements in individuals with ALS compared to controls. Conclusion The findings suggest that individuals with ALS produce excessive jaw opening movements in the absence of excessive jaw closing movements. The lack of excessive jaw closing movements results in reduced tongue raising in these individuals. Excessive jaw opening movements alone suggest a direction-specific jaw dysfunction. Future studies should examine whether excessive jaw raising can be facilitated and if it enhances tongue raising movement for speech production in individuals with dysarthria secondary to ALS.

Articulation contact pressures scaled to the physiologic range of the tongue in amyotrophic lateral sclerosis: A pilot study

OBJECTIVE

The aim of this study was to compare the percentage of the maximum isometric lingual strength range at which lingual-alveolar consonants are produced (%P_max) by people with amyotrophic lateral sclerosis (PALS) compared to people without the disease measured at study entry, and then 3 and 6 months later.

DESIGN

Prospective cohort comparison study over time.

METHODS

Ten people with ALS and nine without produced the consonants /t, d, s, z, l, n/ in real words within sentences as the articulatory contact pressure (ACP) between the tongue tip and palate was sensed by a miniature transducer. Maximum isometric tongue pressing values also were obtained to allow calculation of %P_max. Data were analyzed to compare PALS with bulbar symptoms, PALS with spinal-only symptoms, and people without ALS.

RESULTS

%P_max did not differ between any of the three participant groups at any of the three measurement times. Maximum isometric pressure did decrease significantly in both ALS groups when comparing baseline to 3- and 6-months later. Maximum pressures remained stable for the non-ALS group at the three measurement times.

CONCLUSION

The results suggest that speech motor activity of the tongue in people with ALS may be scaled relative to their overall tongue strength, such that the %P_max does not change as the tongue gets progressively weaker.

Tongue- and Jaw-Specific Articulatory Underpinnings of Reduced and Enhanced Acoustic Vowel Contrast in Talkers With Parkinson's Disease

Purpose This study sought to identify the articulator-specific mechanisms that underlie reduced and enhanced acoustic vowel contrast in talkers with dysarthria due to Parkinson's disease (PD). Method Seventeen talkers with mild-moderate dysarthria due to PD and 17 controls completed a sentence repetition task using typical, slow, loud, and clear speech. Tongue and jaw articulatory movements were recorded using 3D electromagnetic articulography. Independent tongue displacements, jaw displacements, and acoustic vowel contrast were calculated for the diphthong /aɪ/ embedded in the word kite. Results During typical speech, independent tongue displacement, but not jaw displacement, contributed significantly to the intertalker variance in acoustic vowel contrast. Loudness-related acoustic vowel contrast gains were predominantly jaw driven in controls but driven by the tongue and jaw in talkers with PD. Further, in both groups, clarity-related acoustic vowel contrast gains were predominantly jaw driven. Finally, in both groups, rate-related acoustic vowel contrast gains were predominantly tongue driven; however, the jaw also contributed. These jaw contributions were greater in the PD group than in the control group. Conclusions Findings suggest that a tongue-specific articulatory impairment underlies acoustic vowel contrast deterioration in talkers with PD, at least during the early stages of speech decline. Findings further suggest that slow speech engages the impaired tongue more than loud and clear speech in talkers with PD. However, slow speech was also associated with an abnormally strong jaw response in these talkers, which suggests that a compensatory articulatory behavior may also be elicited.

Vowel-Specific Intelligibility and Acoustic Patterns in Individuals With Dysarthria Secondary to Amyotrophic Lateral Sclerosis

Purpose The purpose of the study was to investigate vowel-specific intelligibility and acoustic patterns of individuals with different severities of dysarthria secondary to amyotrophic lateral sclerosis (ALS). Method Twenty-three individuals with dysarthria secondary to ALS and 22 typically aging individuals participated as speakers. Participants with ALS were divided into 2 severity groups (severe, mild). For vowel-specific intelligibility data, 135 listeners participated in the study. Vowel-specific intelligibility, intrinsic vowel duration, 1st and 2nd formants (F1 and F2), vowel inherent spectral change (VISC), and absolute VISC were examined. Results A significant interaction between severity group and the vowel-specific intelligibility pattern as well as F1, F2 VISC, and absolute F2 VISC was observed. Specifically, individuals with severe dysarthria showed a significantly less intelligible /ɪ/ than /ɛ/, unlike individuals with mild dysarthria and typically aging individuals. In addition, vowel intelligibility of /ɪ/ showed the strongest association to the severity measures in individuals with ALS. A number of vowel-specific findings are reported in the acoustic variables. Acoustic correlates of vowel-specific intelligibility were identified. Conclusion Vowel-specific intelligibility patterns are different across severity groups; particularly, low intelligibility of /ɪ/ was noted in individuals with severe dysarthria. Individuals with dysarthria maintained the acoustic contrast in duration and F1 VISC among vowels but did not maintain the other spectral contrasts. Reduction of acoustic vowel space was observed primarily due to high F1 in high vowels in individuals with severe dysarthria. Regression findings suggest that the high F1 values of high and mid vowels and F2 reduction of high- and mid-front vowels decreased vowel-specific intelligibility. In addition, vowel duration influenced the vowel intelligibility of vowels that required short intrinsic vowel duration. Lastly, F2 VISC influenced the vowel intelligibility of /ɪ/. Overall, the vowel-specific intelligibility pattern is related to both vowel-specific characteristics and group-specific articulatory control dysfunction.

A first investigation of tongue, lip, and jaw movements in persons with dysarthria due to multiple sclerosis

BACKGROUND

Multiple sclerosis can affect the speech motor system and result in dysarthria.

OBJECTIVES

This pilot study sought to identify tongue, lip, and jaw motor deficits in persons with dysarthria due to multiple sclerosis (PwDMS) to better understand the speech motor mechanisms that underlie their aberrant speech.

METHODS

Tongue and jaw movements during "ai" and lower lip and jaw movements during "bob"were examined in eleven PwDMS and fourteen age- and sex-matched controls using three-dimensional electromagnetic articulography. Movement duration, maximum displacement, peak speed, stiffness (i.e., peak speed/displacement ratio), and jaw contribution to lower lip and tongue displacements were of particular interest.

RESULTS

Whereas most kinematic measures yielded significant between-group differences for tongue and jaw motor performance during "ai", lower lip and jaw motor performance during "bob" were mostly comparable between groups.

CONCLUSION

Findings suggest that speech movements of the tongue are differentially more impaired than those of the lower lip in PwDMS. Particularly the ability to move the tongue with adequate speed during speech was significantly impaired in PwDMS, which may explain, in part, their slowed speech rate. Aberrant jaw kinematics during "ai" may be a compensatory strategy to maximize speech clarity in the presence of the impaired tongue motor performance.

Articulatory Range of Movement in Individuals With Dysarthria Secondary to Amyotrophic Lateral Sclerosis

PURPOSE

The current study examined overall articulatory range of movement (ROM) in individuals with amyotrophic lateral sclerosis (ALS). Differential involvement of articulators was also tested using articulatory working space in individuals with varying degrees of dysarthria severity and in typically aging individuals. A strong association between overall articulatory ROM and severity measures among individuals with ALS was hypothesized. In addition, it was hypothesized that differential involvement of articulators would be detected using overall articulatory ROM measures.

METHOD

Twenty-two speakers with dysarthria secondary to ALS and 22 typically aging speakers participated. Speech intelligibility and speaking rate were used as indices of severity. Movement range and overall articulatory working space area (convex hull) of the tongue, lower lip, and jaw were each measured by electromagnetic articulography while the speakers produced the Rainbow Passage.

RESULTS

Tongue convex hull size was significantly correlated with both indices of severity. A significant interaction between articulators and groups was observed. Individuals with severe dysarthria had reduced tongue convex hull size and exaggerated lower lip convex hull size. ROM in the anterior-posterior dimension showed a more notable differential involvement pattern than ROM in the superior-inferior dimension. Results in the area under a receiver operating characteristic curve analysis revealed group-specific ROM sensitivity.

CONCLUSIONS

The findings indicate that tongue ROM is reduced in individuals with more severe dysarthria when estimated using a standardized paragraph containing all American English phonemes. The articulatory working space measure could be useful for estimating speech dysfunction in ALS. ROM of the tongue decreases, but ROM of the lower lip and jaw each increase in individuals with severe dysarthria. Differential involvement of the articulators in the anterior-posterior dimension needs to be further investigated.