The Contributions of Pitch, Loudness, and Rate Control to Speech Naturalness in Cerebellar Ataxia.

PURPOSE: The goal of this study was to determine the relationship between the perceptual measure of speech naturalness and objective measures of pitch, loudness, and rate control as a potential tool for assessment of ataxic dysarthria. METHOD: Twenty-seven participants with ataxia and 29 age- and sex-matched control participants completed the pitch glide and loudness step tasks drawn from the Frenchay Dysarthria Assessment-Second Edition (FDA-2) in addition to speech diadochokinetic (DDK) tasks. First, group differences were compared for pitch variability in the pitch glide task, loudness variability in the loudness step task, and syllable duration and speech rate in the DDK task. Then, these acoustic measures were compared with previously collected ratings of speech naturalness by speech-language pathology graduate students. RESULTS: Robust group differences were measured for pitch variability and both DDK syllable duration and speech rate, indicating that the ataxia group had greater pitch variability, longer DDK syllable duration, and slower DDK speech rate than the control group. No group differences were measured for loudness variability. There were robust relationships between speech naturalness and pitch variability, DDK syllable duration, and DDK speech rate, but not for loudness variability. CONCLUSIONS: Objective acoustic measures of pitch variability in the FDA-2 pitch glide task and syllable duration and speech rate in the DDK task can be used to validate perceptual measures of speech naturalness. Overall, speech-language pathologists can incorporate both perceptual measures of speech naturalness and acoustic measures of pitch variability and DDK performance for a comprehensive evaluation of ataxic dysarthria.

Tipping the Scales: Indiscriminate Use of Interval Scales to Rate Diverse Dysarthric Features.

PURPOSE: Error related to incorrect use of rating scales is problematic in the assessment and treatment of dysarthria. The main purpose of this project was to determine scale fit for cardinal speech features of hypokinetic dysarthria. A secondary aim was to determine rater reliability for the two different scales explored. METHOD: Forty-three speakers with Parkinson's disease (PD) and 25 neurologically healthy control talkers were recorded reading sentences from the Speech Intelligibility Test. Twenty-two healthy female listeners used both an equal appearing interval (EAI) scale and a direct magnitude estimation (DME) scale to rate five perceptual speech features (i.e., overall speech severity, articulatory imprecision, reduced loudness, short rushes of speech, and monotony) from these recordings. Regression analyses were used to determine the linearity of the relationship between the means of the EAI and DME ratings. Inter- and intrarater reliability was calculated using intraclass correlation coefficients and Spearman's correlation coefficients, respectively, for both EAI and DME ratings. RESULTS: There was a linear relationship between EAI and DME means for monotony, indicating it is a metathetic dimension. Curvilinear relationships were observed between the EAI and DME means for the other four features, indicating prothetic dimensions. Intra- and interrater reliability values were similar for EAI and DME ratings. DISCUSSION: Overall, results of this work suggest that DME is the best fit for scaling several hypokinetic dysarthria features, and not the conventionally used EAI scale. Prothetic dimensions best scaled by DME include overall speech severity, articulatory imprecision, reduced loudness, and short rushes of speech. Monotony was the only feature found to be a metathetic dimension and would be best scaled using EAI or DME. Findings call for rethinking the widespread use of EAI scales for rating perceptual features as part of the assessment and treatment of motor speech disorders.

Higher Frequency of Stuttered Disfluencies Negatively Affects Communicative Participation in Parkinson's Disease.

PURPOSE: Up to 90% of people with Parkinson's disease (PD) develop communication difficulties over the course of the disease. While the negative effect of dysarthria on communicative participation has been well-documented, the impact of the occurrence of acquired stuttered disfluencies on communication in different speech situations is unknown. This study aimed to determine if the frequency of occurrence of stuttered disfluencies affects communicative participation in individuals with PD, and whether such a relationship is mediated by examiner- and self-rated measures of disease severity. METHOD: Conversational speech samples were collected from 100 people with PD aged 53-91 years to calculate the frequency of occurrence of stuttered disfluencies. Participants completed the Communicative Participation Item Bank to assess participation in communicative situations. Information on overall speech, cognitive, and motor performance was collected using both self-rated and examiner-rated methods. RESULTS: Participants with PD presented with 0.2%-9.9% stuttered disfluencies during conversation. Overall, participants with PD reported their communicative participation to be impacted "a little" (19.5 ± 7.0), but there was considerable interindividual variation. A higher frequency of stuttered disfluencies was associated with significantly lower communicative participation (ρ = -0.32, p < .01). In addition, examiner-rated frequency of stuttered disfluencies (p < .01), speech (p < .01), and motor severity (p = .04) were all significant predictors of communicative participation. Using self-ratings, speech (p < .01) and cognitive (p < .01) measures significantly predicted communicative participation. CONCLUSIONS: In people with PD, communicative participation was significantly worse for those with a higher frequency of stuttered disfluencies. Examiner- and self-rated measures of disease severity contributed different information related to communicative constraints. Together, these results highlight the importance of individualized and holistic speech therapy that considers a wide variety of symptoms, including stuttered disfluencies, to ensure positive functional outcomes. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.26850169.

Dysarthria-clumsy hand syndrome and multiple sequential acute limb embolisms as a form of presentation of aortic arch embolism. / Síndrome de disartria-mano torpe y embolias agudas secuenciales múltiples de las extremidades como forma de presentación de un trombo del cayado aórtico.

INTRODUCTION: Aortic arch complex atheromatosis is a source of cerebral embolism. A percentage of lacunar infarct could be of embolic etiology, especially due to microemboli of the aortic arch. CASE REPORT: We present the case of a 63-year-old hypertensive man suffering from dysarthria-clumsy hand syndrome for a right hemispheric minor ischemic stroke. The patient developed sequential acute thromboembolism of the left lower and right upper limbs. Computed tomography angiography revealed an aortic arch thrombus. Vascular surgery was successfully performed. CONCLUSION: This case highlights the importance of considering embolic sources in lacunar syndromes, especially at the level of the aortic arch.

TITLE: Síndrome de disartria-mano torpe y embolias agudas secuenciales múltiples de las extremidades como forma de presentación de un trombo del cayado aórtico.Introducción. La ateromatosis del complejo del arco aórtico es una fuente de embolia cerebral. Un porcentaje de infartos lacunares podría ser de etiología embólica, especialmente debidos a microembolias del arco aórtico. Caso clínico. Presentamos el caso de un varón hipertenso de 63 años con síndrome de disartria-mano torpe por un ictus isquémico minor hemisférico derecho. El paciente desarrolló un tromboembolismo agudo secuencial de los miembros inferior izquierdo y superior derecho. La angiografía por tomografía computarizada reveló un trombo en el arco aórtico. La cirugía vascular se llevó a cabo con éxito. Conclusión. Este caso destaca la importancia de considerar las fuentes embólicas en los síndromes lacunares, especialmente en el arco aórtico.

Introduction to the Forum: Native Language, Dialect, and Foreign Accent in Dysarthria.

This timely collection is an international effort to serve as a foundation to encourage research that offers insights into the interaction between language variation and motor speech disorders. Specifically, this forum aimed to provide a platform that (a) explores and demonstrates the role of language variation in the manifestation of dysarthria, (b) considers language variation in clinical assessment and management, and (c) promotes awareness of diverse language backgrounds of people with dysarthria. The forum contains six articles, spanning a variety of research designs (cross-sectional, pre- and post-treatment), kinds of articles (tutorial, research article, commentary), and a range of languages from around the world (English, French, Korean Portuguese, Spanish).

Acoustic and Kinematic Predictors of Intelligibility and Articulatory Precision in Parkinson's Disease.

PURPOSE: This study investigated relationships within and between perceptual, acoustic, and kinematic measures in speakers with and without dysarthria due to Parkinson's disease (PD) across different clarity conditions. Additionally, the study assessed the predictive capabilities of selected acoustic and kinematic measures for intelligibility and articulatory precision ratings. METHOD: Forty participants, comprising 22 with PD and 18 controls, read three phrases aloud using conversational, less clear, and more clear speaking conditions. Acoustic measures and their theoretical kinematic parallel measures (i.e., acoustic and kinematic distance and vowel space area [VSA]; second formant frequency [F2] slope and kinematic speed) were obtained from the diphthong /aɪ/ and selected vowels in the sentences. A total of 368 listeners from crowdsourcing provided ratings for intelligibility and articulatory precision. The research questions were examined using correlations and linear mixed-effects models. RESULTS: Intelligibility and articulatory precision ratings were highly correlated across all speakers. Acoustic and kinematic distance, as well as F2 slope and kinematic speed, showed moderately positive correlations. In contrast, acoustic and kinematic VSA exhibited no correlation. Among all measures, acoustic VSA and kinematic distance were robust predictors of both intelligibility and articulatory precision ratings, but they were stronger predictors of articulatory precision. CONCLUSIONS: The findings highlight the importance of measurement selection when examining cross-domain relationships. Additionally, they support the use of behavioral modifications aimed at eliciting larger articulatory gestures to improve intelligibility in individuals with dysarthria due to PD. OPEN SCIENCE FORM: https://doi.org/10.23641/asha.27011281.

Contributions of Speech Timing and Articulatory Precision to Listener Perceptions of Intelligibility and Naturalness in Parkinson's Disease.

PURPOSE: Parkinson's disease (PD) results in hypokinetic dysarthria in as many as 90% of cases. Among the most distinctive features of hypokinetic dysarthria are atypical timing and articulatory imprecision in speech production. Here, we examined the contributions of perceived speech timing typicality and articulatory precision, both on their own and while controlling for the other, on intelligibility and naturalness in speakers with PD. METHOD: Twenty speakers with PD and four healthy older adults read aloud the first paragraph of the Rainbow Passage. Twenty inexperienced listeners with typical hearing listened to these recordings and rated intelligibility, naturalness, timing typicality, and articulatory precision using separate visual analog scales. Ratings were averaged across listeners and entered into linear regression models with intelligibility and naturalness as dependent variables and timing typicality and articulatory precision as independent variables in each. RESULTS: Articulatory precision, but not timing typicality, was positively correlated with intelligibility on its own, but neither was associated with intelligibility after accounting for the other. Both timing typicality and articulatory precision were positively correlated with naturalness on their own as well as after controlling for the other variable. CONCLUSION: These results contribute to the overall understanding of speech factors associated with intelligibility and naturalness in speakers with PD and indicate that considering the unique contributions of related perceptual constructs may provide more information than bivariate relationships alone.

An Accurate and Rapidly Calibrating Speech Neuroprosthesis.

BACKGROUND: Brain-computer interfaces can enable communication for people with paralysis by transforming cortical activity associated with attempted speech into text on a computer screen. Communication with brain-computer interfaces has been restricted by extensive training requirements and limited accuracy. METHODS: A 45-year-old man with amyotrophic lateral sclerosis (ALS) with tetraparesis and severe dysarthria underwent surgical implantation of four microelectrode arrays into his left ventral precentral gyrus 5 years after the onset of the illness; these arrays recorded neural activity from 256 intracortical electrodes. We report the results of decoding his cortical neural activity as he attempted to speak in both prompted and unstructured conversational contexts. Decoded words were displayed on a screen and then vocalized with the use of text-to-speech software designed to sound like his pre-ALS voice. RESULTS: On the first day of use (25 days after surgery), the neuroprosthesis achieved 99.6% accuracy with a 50-word vocabulary. Calibration of the neuroprosthesis required 30 minutes of cortical recordings while the participant attempted to speak, followed by subsequent processing. On the second day, after 1.4 additional hours of system training, the neuroprosthesis achieved 90.2% accuracy using a 125,000-word vocabulary. With further training data, the neuroprosthesis sustained 97.5% accuracy over a period of 8.4 months after surgical implantation, and the participant used it to communicate in self-paced conversations at a rate of approximately 32 words per minute for more than 248 cumulative hours. CONCLUSIONS: In a person with ALS and severe dysarthria, an intracortical speech neuroprosthesis reached a level of performance suitable to restore conversational communication after brief training. (Funded by the Office of the Assistant Secretary of Defense for Health Affairs and others; BrainGate2 ClinicalTrials.gov number, NCT00912041.).

Prosody matters: Preserved prominence marking strategies in people with Parkinson's disease independent of motor status.

While many studies focus on segmental variation in Parkinsonian speech, little is known about prosodic modulations reflecting the ability to adapt to communicative demands in people with Parkinson's disease (PwPD). This type of prosodic modulation is important for social interaction, and it involves modifications in speech melody (intonational level) and articulation of consonants and vowels (segmental level). The present study investigates phonetic cues of prosodic modulations with respect to different focus structures in mild dysarthric PwPD as a function of levodopa. Acoustic and kinematic speech parameters of 25 PwPD were assessed in two motor conditions. Speech production data from PwPD were collected before (medication-OFF) and after levodopa intake (medication-ON) by means of 3-D electromagnetic articulography. On the acoustic level, intensity, pitch, and syllable durations were analyzed. On the kinematic level, movement duration and amplitude were investigated. Spatio-temporal modulations of speech parameters were examined and compared across three different prosodic focus structures (out-of-focus, broad focus, contrastive focus) to display varying speech demands. Overall, levodopa had beneficial effects on motor performance, speech loudness, and pitch modulation. Acoustic syllable durations and kinematic movement durations did not change, revealing no systematic effects of motor status on the temporal domain. In contrast, there were spatial modulations of the oral articulators: tongue tip movements were smaller and lower lip movements were larger in amplitude under levodopa, reflecting a more agile and efficient articulatory movement under levodopa. Thus, respiratory-phonatory functions and consonant production improved, while syllable duration and tongue body kinematics did not change. Interestingly, prominence marking strategies were comparable between the medication conditions under investigation, and in fact, appear to be preserved in mild dysarthric PwPD.

Voice signals database of ALS patients with different dysarthria severity and healthy controls.

This paper describes a new publicly-available database of VOiCe signals acquired in Amyotrophic Lateral Sclerosis (ALS) patients (VOC-ALS) and healthy controls performing different speech tasks. This dataset consists of 1224 voice signals recorded from 153 participants: 51 healthy controls (32 males and 19 females) and 102 ALS patients (65 males and 37 females) with different severity of dysarthria. Each subject's voice was recorded using a smartphone application (Vox4Health) while performing several vocal tasks, including a sustained phonation of the vowels /a/, /e/, /i/, /o/, /u/ and /pa/, /ta/, /ka/ syllable repetition. Basic derived speech metrics such as harmonics-to-noise ratio, mean and standard deviation of fundamental frequency (F0), jitter and shimmer were calculated. The F0 standard deviation of vowels and syllables showed an excellent ability to identify people with ALS and to discriminate the different severity of dysarthria. These data represent the most comprehensive database of voice signals in ALS and form a solid basis for research on the recognition of voice impairment in ALS patients for use in clinical applications.

Lee Silverman voice treatment versus NHS speech and language therapy versus control for dysarthria in people with Parkinson's disease (PD COMM): pragmatic, UK based, multicentre, three arm, parallel group, unblinded, randomised controlled trial.

OBJECTIVES: To assess the clinical effectiveness of two speech and language therapy approaches versus no speech and language therapy for dysarthria in people with Parkinson's disease. DESIGN: Pragmatic, UK based, multicentre, three arm, parallel group, unblinded, randomised controlled trial. SETTING: The speech and language therapy interventions were delivered in outpatient or home settings between 26 September 2016 and 16 March 2020. PARTICIPANTS: 388 people with Parkinson's disease and dysarthria. INTERVENTIONS: Participants were randomly assigned to one of three groups (1:1:1): 130 to Lee Silverman voice treatment (LSVT LOUD), 129 to NHS speech and language therapy, and 129 to no speech and language therapy. LSVT LOUD consisted of four, face-to-face or remote, 50 min sessions each week delivered over four weeks. Home based practice activities were set for up to 5-10 mins daily on treatment days and 15 mins twice daily on non-treatment days. Dosage for the NHS speech and language therapy was determined by the local therapist in response to the participants' needs (estimated from prior research that NHS speech and language therapy participants would receive an average of one session per week over six to eight weeks). Local practices for NHS speech and language therapy were accepted, except for those within the LSVT LOUD protocol. Analyses were based on the intention to treat principle. MAIN OUTCOME MEASURES: The primary outcome was total score at three months of self-reported voice handicap index. RESULTS: People who received LSVT LOUD reported lower voice handicap index scores at three months after randomisation than those who did not receive speech and language therapy (-8.0 points (99% confidence interval -13.3 to -2.6); P<0.001). No evidence suggests a difference in voice handicap index scores between NHS speech and language therapy and no speech and language therapy (1.7 points (-3.8 to 7.1); P=0.43). Patients in the LSVT LOUD group also reported lower voice handicap index scores than did those randomised to NHS speech and language therapy (-9.6 points (-14.9 to -4.4); P<0.001). 93 adverse events (predominately vocal strain) were reported in the LSVT LOUD group, 46 in the NHS speech and language therapy group, and none in the no speech and language therapy group. No serious adverse events were recorded. CONCLUSIONS: LSVT LOUD was more effective at reducing the participant reported impact of voice problems than was no speech and language therapy and NHS speech and language therapy. NHS speech and language therapy showed no evidence of benefit compared with no speech and language therapy. TRIAL REGISTRATION: ISRCTN registry ISRCTN12421382.

Analysis of events from sudden isolated dysarthria to diagnosis of myasthenic crisis: myasthenia gravis mimicking acute lacunar stroke-a case report.

BACKGROUND: Myasthenic crisis (MC) is a life-threatening complication of myasthenia gravis (MG), necessitating ventilation. Achieving a safe and timely diagnosis of myasthenic crisis with atypical, isolated presentation is a considerable challenge particularly in elderly patients, where myasthenia gravis can present with isolated dysarthria in rare instances, giving a clinical impression of lacunar stroke. CASE PRESENTATION: We present a compelling case of a 73-year-old Caucasian female presenting with abrupt onset of isolated dysarthria. Despite initial treatment for a presumed lacunar stroke, subsequent evaluations led to her diagnosis of a myasthenic crisis. Within 72 h of admission, the patient developed dysphagia and shortness of breath, requiring supplemental oxygen. The case highlights the sequential progression of events from the atypical presentation of isolated dysarthria and its course to the management of a myasthenic crisis. CONCLUSION: Our reported case focuses on the discussion of myasthenia that mimicked a lacunar stroke and was finally diagnosed at a critical time of medical crisis. This case highlights the imperative notion that isolated dysarthria in elderly individuals warrants vigilant monitoring for possible myasthenia gravis, given the low incidence of lacunar stroke presenting with only dysarthria.

GLUT1DS focus on dysarthria.

RESEARCH PURPOSE: GLUT1 deficiency syndrome (GLUT1DS) is a rare genetic disorder caused by a mutation in the SLC2A1 gene that limits the transport of glucose across the blood-brain barrier. Speech disorders and dysarthria are typical findings in patients with GLUT1DS, but have never been deeply phenotyped. The aim of the present study was to characterize speech abilities in a sample of patients with GLUT1DS. RESULTS: 30 patients with GLUT1DS were recruited. We reported impairments in different speech and oromotor domains: the speech was characterized by dysarthria, inaccurate articulation of consonants, abnormal nasal resonance, errors in intonation and prosody and low intelligibility. We observed difficulties in motor planning and programming. Moreover, we observed a significant difference between the dysarthric level of impairment with genotype groups. CONCLUSIONS: The presence of a speech disorder in patients with GLUT1DS represents a core feature of the syndrome. Our findings suggest that patients with GLUT1DS would benefit from a comprehensive neurocognitive assessment to detect strengths and weaknesses of the speech profile. Understanding the speech and language phenotype in GLUT1DS is critical for planning early intervention to positively influence the global development of patients with GLUT1DS.

Dysarthria and dysphagia in patients with mitochondrial diseases.

BACKGROUND: Information about dysarthria and dysphagia in mitochondrial diseases (MD) is scarce. However, this knowledge is needed to identify speech and swallowing problems early, to monitor the disease course, and to develop and offer optimal treatment and support. This study therefore aims to examine the prevalence and severity of dysarthria and dysphagia in patients with MD and its relation to clinical phenotype and disease severity. Secondary aim is to determine clinically relevant outcome measures for natural history studies and clinical trials. METHODS: This retrospective cross-sectional medical record study includes adults (age ≥ 18 years) diagnosed with genetically confirmed MD who participated in a multidisciplinary admission within the Radboud center for mitochondrial medicine between January 2015 and April 2023. Dysarthria and dysphagia were examined by administering the Radboud dysarthria assessment, swallowing speed, dysphagia limit, test of mastication and swallowing solids (TOMASS), and 6-min mastication test (6MMT). The disease severity was assessed using the Newcastle mitochondrial disease scale for adults (NMDAS). RESULTS: The study included 224 patients with MD with a median age of 42 years of whom 37.5% were male. The pooled prevalence of dysarthria was 33.8% and of dysphagia 35%. Patients with MD showed a negative deviation from the norm on swallowing speed, TOMASS (total time) and the 6MMT. Furthermore, a significant moderate relation was found between the presence of dysarthria and the clinical phenotypes. There was a statistically significant difference in total time on the TOMASS between the clinical phenotypes. Finally, disease severity showed a significant moderate relation with the severity of dysarthria and a significant weak relation with the severity of dysphagia. CONCLUSION: Dysarthria and dysphagia occur in about one-third of patients with MD. It is important for treating physicians to pay attention to this subject because of the influence of both disorders on social participation and wellbeing. Referral to a speech and language therapist should therefore be considered, especially in patients with a more severe clinical phenotype. The swallowing speed, TOMASS and 6MMT are the most clinically relevant tests to administer.

Effects of SPEAK OUT! & LOUD Crowd on Functional Speech Measures in Parkinson's Disease.

PURPOSE: This study investigated the effects of the SPEAK OUT! & LOUD Crowd therapy program on speaking rate, percent pause time, intelligibility, naturalness, and communicative participation in individuals with Parkinson's disease (PD). METHOD: Six adults with PD completed 12 individual SPEAK OUT! sessions across four consecutive weeks followed by group-based LOUD Crowd sessions for five consecutive weeks. Most therapy sessions were conducted via telehealth, with two participants completing the SPEAK OUT! portion in person. Speech samples were recorded at six time points: three baseline time points prior to SPEAK OUT!, two post-SPEAK OUT! time points, and one post-LOUD Crowd time point. Acoustic measures of speaking rate and percent pause time and listener ratings of speech intelligibility and naturalness were obtained for each time point. Participant self-ratings of communicative participation were also collected at pre- and posttreatment time points. RESULTS: Results showed significant improvement in communicative participation scores at a group level following completion of the SPEAK OUT! & LOUD Crowd treatment program. Two participants showed a significant decrease in speaking rate and increase in percent pause time following treatment. Changes in intelligibility and naturalness were not statistically significant. CONCLUSIONS: These findings provide preliminary support for the effectiveness of the SPEAK OUT! & LOUD Crowd treatment program in improving communicative participation for people with mild-to-moderate hypokinetic dysarthria secondary to PD. This study is also the first to demonstrate positive effects of this treatment program for people receiving the therapy via telehealth.

The Effects of Interactive Context on Acoustic Characteristics of Speech in People With Dysarthria: A Preliminary Study.

PURPOSE: The current study compared temporal and spectral acoustic contrast between vowel segments produced by speakers with dysarthria across three speech tasks-interactive, solo habitual, and solo clear. METHOD: Nine speakers with dysarthria secondary to amyotrophic lateral sclerosis participated in the study. Each speaker was paired with a typical interlocutor over videoconferencing software. The speakers produced the vowels /i, ɪ, ɛ, æ/ in /h/-vowel-/d/ words. For the solo tasks, speakers read the stimuli aloud in both their habitual and clear speaking styles. For the interactive task, speakers produced a target stimulus for their interlocutor to select among the four possibilities. We measured the duration difference between long and short vowels, as well as the F1/F2 Euclidean distance between adjacent vowels, and also determined how well the vowels could be classified based on their acoustic characteristics. RESULTS: Temporal contrast between long and short vowels was higher in the interactive task than in both solo tasks. Spectral distance between adjacent vowel pairs was also higher for some pairs in the interactive task than the habitual speech task. Finally, vowel classification accuracy was highest in the interactive task. CONCLUSIONS: Overall, we found evidence that individuals with dysarthria produced vowels with greater acoustic contrast in structured interactions than they did in solo tasks. Furthermore, the speech adjustments they made to the vowel segments differed from those observed in solo speech.

Differential spectral characteristics of the Spanish fricative /s/ in the articulation of individuals with dysarthria and apraxia of speech.

PURPOSE: This study examines whether there are differences in the speech of speakers with dysarthria, speakers with apraxia and healthy speakers in spectral acoustic measures during production of the central-peninsular Spanish alveolar sibilant fricative /s/. METHOD: To this end, production of the sibilant was analyzed in 20 subjects with dysarthria, 8 with apraxia of speech and 28 healthy speakers. Participants produced 12 sV(C) words. The variables compared across groups were the fricative's spectral amplitude difference (AmpD) and spectral moments in the temporal midpoint of fricative execution. RESULTS: The results indicate that individuals with dysarthria can be distinguished from healthy speakers in terms of the spectral characteristics AmpD, standard deviation (SD), center of gravity (CoG) and skewness, the last two in context with unrounded vowel, while no differences in kurtosis were detected. Participants with AoS group differ significantly from healthy speaker group in AmpD, SD and CoG and Kurtosis, the first one followed unrounded vowel and the latter two followed by rounded vowels. In addition, speakers with apraxia of speech group returned significant differences with respect to speakers with dysarthria group in AmpD, CoG and skewness. CONCLUSIONS: The differences found between the groups in the measures studied as a function of the type of vowel context could provide insights into the distinctive manifestations of motor speech disorders, contributing to the differential diagnosis between apraxia and dysarthria in motor control processes.