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Dysarthria is a common and debilitating symptom of many neurodegenerative diseases, including those resulting in ataxia. Changes to speech lead to significant reductions in quality of life, impacting the speaker in most daily activities. Recognition of its importance as an objective outcome measure in clinical trials for ataxia is growing. Its viability as an endpoint across the disease spectrum (i.e. pre-symptomatic onwards) means that trials can recruit ambulant individuals and later-stage individuals who are often excluded because of difficulty completing lower limb tasks. Here we discuss the key considerations for speech testing in clinical trials including hardware selection, suitability of tasks and their role in protocols for trials and propose a core set of tasks for speech testing in clinical trials. Test batteries could include forms suitable for remote short, sensitive and easy to use, with norms available in several languages. The use of artificial intelligence also could improve accuracy and automaticity of analytical pipelines in clinic and trials., (© 2023. The Author(s).)

This study characterizes the speech phenotype of spinocerebellar ataxia type 1 (SCA1) using both perceptual and objective acoustic analysis of speech in a cohort of SCA1 patients. Twenty-seven symptomatic SCA1 patients in various disease stages (SARA score range: 3-32 points) and 18 sex and age matched healthy controls underwent a clinical assessment addressing ataxia severity, non-ataxia signs, cognitive functioning, and speech. Speech samples were perceptually rated by trained speech therapists, and acoustic metrics representing speech timing, vocal control, and voice quality were extracted. Perceptual analysis revealed reduced intelligibility and naturalness in speech samples of SCA1 patients. Acoustically, SCA1 patients presented with slower speech rate and diadochokinetic rate as well as longer syllable duration compared to healthy controls. No distinct abnormalities in voice quality in the acoustic analysis were detected at group level. Both the affected perceptual and acoustic variables correlated with ataxia severity. Longitudinal assessment of speech is needed to place changes in speech in the context of disease progression and potential response to treatment., (© 2023. The Author(s).)

Purpose: The human voice changes with the progression of neurological disease and the onset of diseases that affect articulators, often decreasing the effectiveness of communication. These changes can be objectively measured using signal processing techniques that extract acoustic features. When measuring acoustic features, there are often several steps and assumptions that might be known to experts in acoustics and phonetics, but are less transparent for other disciplines (e.g., clinical medicine, speech pathology, engineering, and data science). This tutorial describes these signal processing techniques, explicitly outlines the underlying steps for accurate measurement, and discusses the implications of clinical acoustic markers., Conclusions: We establish a vocabulary using straightforward terms, provide visualizations to achieve common ground, and guide understanding for those outside the domains of acoustics and auditory signal processing. Where possible, we highlight the best practices for measuring clinical acoustic markers and suggest resources for obtaining and further understanding these measures.

Speech production relies on motor control and cognitive processing and is linked to cerebellar function. In diseases where the cerebellum is impaired, such as multiple sclerosis (MS), speech abnormalities are common and can be detected by instrumental assessments. However, the potential of speech assessments to be used to monitor cerebellar impairment in MS remains unexplored. The aim of this study is to build an objectively measured speech score that reflects cerebellar function, pathology and quality of life in MS. Eighty-five people with MS and 21 controls participated in the study. Speech was independently assessed through objective acoustic analysis and blind expert listener ratings. Cerebellar function and overall disease disability were measured through validated clinical scores; cerebellar pathology was assessed via magnetic resonance imaging, and validated questionnaires informed quality of life. Selected speech variables were entered in a regression model to predict cerebellar function. The resulting model was condensed into one composite speech score and tested for prediction of abnormal 9-hole peg test (9HPT), and for correlations with the remaining cerebellar scores, imaging measurements and self-assessed quality of life. Slow rate of syllable repetition and increased free speech pause percentage were the strongest predictors of cerebellar impairment, complemented by phonatory instability. Those variables formed the acoustic composite score that accounted for 54% of variation in cerebellar function, correlated with cerebellar white matter volume (r = 0.3, p = 0.017), quality of life (r = 0.5, p < 0.001) and predicted an abnormal 9HPT with 85% accuracy. An objective multi-feature speech metric was highly representative of motor cerebellar impairment in MS.

Subtle motor and cognitive changes can manifest prior to diagnosis in many progressive neurological disorders. Most people with Huntington's disease (HD) develop dysarthria. Yet, how speech evolves, how the brain regulates speech in HD, and the clinical implications of these changes remain unclear. We reviewed existing literature on speech production in premanifest (PreHD) to symptomatic HD. A search of databases yielded 12 eligible studies. Nine of the twelve studies were included in the meta-analysis. Data suggest that speech in PreHD is characterized by impaired speech agility, phonatory function and speech rate. Over the disease course, speech gradually deteriorates across all subsystems of speech. Our findings indicate subtle changes in speech appear prior to a clinical diagnosis of HD. However, distinct patterns of decline and the magnitude of these deficits require further investigation. Our current understanding of speech impairment in HD relies on small cohort studies. Natural history studies documenting changes from premanifest to end stage may facilitate the development of speech as a marker of disease onset and treatment response., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Importance: Multiple sclerosis produces neurological impairments that are variable in duration, severity and quality. Speech is frequently impaired, resulting in decreased communication skills and quality of life. Advancements in technology now makes it possible to use quantitative acoustic assessment of speech as biomarkers of disease progression., Observations: Four domains of speech have been identified: articulation (slow articulation and imprecise consonants), voice (pitch and loudness instability), respiration (decreased phonatory time and expiratory pressure) and prosody (longer and frequent pauses, deficient loudness control). Studies also explored I) predictive models for diagnosis of MS and of ataxia using speech variables, II) the relationship of dysarthria with cognition and III) very few studies correlated neuroimaging with dysarthria. We could not identify longitudinal studies of speech or dysarthria in Multiple Sclerosis., Conclusion and Relevance: Refinement of objective measures of speech has enhanced our understanding of Multiple Sclerosis-related deficits in cross-sectional analysis while both integrative and longitudinal studies are identified as major gaps. This review highlights the potential for using quantitative acoustic assessments as clinical endpoints for diagnosing, monitoring progression and treatment in disease modifying trials., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: To provide a comprehensive description of motor speech function in behavioral variant frontotemporal dementia (bvFTD)., Methods: Forty-eight individuals (24 bvFTD and 24 age- and sex-matched healthy controls) provided speech samples. These varied in complexity and thus cognitive demand. Their language was assessed using the Progressive Aphasia Language Scale and verbal fluency tasks. Speech was analyzed perceptually to describe the nature of deficits and acoustically to quantify differences between patients with bvFTD and healthy controls. Cortical thickness and subcortical volume derived from MRI scans were correlated with speech outcomes in patients with bvFTD., Results: Speech of affected individuals was significantly different from that of healthy controls. The speech signature of patients with bvFTD is characterized by a reduced rate (75%) and accuracy (65%) on alternating syllable production tasks, and prosodic deficits including reduced speech rate (45%), prolonged intervals (54%), and use of short phrases (41%). Groups differed on acoustic measures derived from the reading, unprepared monologue, and diadochokinetic tasks but not the days of the week or sustained vowel tasks. Variability of silence length was associated with cortical thickness of the inferior frontal gyrus and insula and speech rate with the precentral gyrus., Conclusions: One in 8 patients presented with moderate speech timing deficits with a further two-thirds rated as mild or subclinical. Subtle but measurable deficits in prosody are common in bvFTD and should be considered during disease management. Language function correlated with speech timing measures derived from the unprepared monologue only., (© 2017 American Academy of Neurology.)

Purpose: Our purpose was to create a comprehensive review of speech impairment in frontotemporal dementia (FTD), primary progressive aphasia (PPA), and progressive apraxia of speech in order to identify the most effective measures for diagnosis and monitoring, and to elucidate associations between speech and neuroimaging., Method: Speech and neuroimaging data described in studies of FTD and PPA were systematically reviewed. A meta-analysis was conducted for speech measures that were used consistently in multiple studies., Results: The methods and nomenclature used to describe speech in these disorders varied between studies. Our meta-analysis identified 3 speech measures which differentiate variants or healthy control-group participants (e.g., nonfluent and logopenic variants of PPA from all other groups, behavioral-variant FTD from a control group). Deficits within the frontal-lobe speech networks are linked to motor speech profiles of the nonfluent variant of PPA and progressive apraxia of speech. Motor speech impairment is rarely reported in semantic and logopenic variants of PPA. Limited data are available on motor speech impairment in the behavioral variant of FTD., Conclusions: Our review identified several measures of speech which may assist with diagnosis and classification, and consolidated the brain-behavior associations relating to speech in FTD, PPA, and progressive apraxia of speech.

Differentiation of logopenic (lvPPA) and nonfluent/agrammatic (nfvPPA) variants of Primary Progressive Aphasia is important yet remains challenging since it hinges on expert based evaluation of speech and language production. In this study acoustic measures of speech in conjunction with voxel-based morphometry were used to determine the success of the measures as an adjunct to diagnosis and to explore the neural basis of apraxia of speech in nfvPPA. Forty-one patients (21 lvPPA, 20 nfvPPA) were recruited from a consecutive sample with suspected frontotemporal dementia. Patients were diagnosed using the current gold-standard of expert perceptual judgment, based on presence/absence of particular speech features during speaking tasks. Seventeen healthy age-matched adults served as controls. MRI scans were available for 11 control and 37 PPA cases; 23 of the PPA cases underwent amyloid ligand PET imaging. Measures, corresponding to perceptual features of apraxia of speech, were periods of silence during reading and relative vowel duration and intensity in polysyllable word repetition. Discriminant function analyses revealed that a measure of relative vowel duration differentiated nfvPPA cases from both control and lvPPA cases (r(2) = 0.47) with 88% agreement with expert judgment of presence of apraxia of speech in nfvPPA cases. VBM analysis showed that relative vowel duration covaried with grey matter intensity in areas critical for speech motor planning and programming: precentral gyrus, supplementary motor area and inferior frontal gyrus bilaterally, only affected in the nfvPPA group. This bilateral involvement of frontal speech networks in nfvPPA potentially affects access to compensatory mechanisms involving right hemisphere homologues. Measures of silences during reading also discriminated the PPA and control groups, but did not increase predictive accuracy. Findings suggest that a measure of relative vowel duration from of a polysyllable word repetition task may be sufficient for detecting most cases of apraxia of speech and distinguishing between nfvPPA and lvPPA.

Speech disturbances (e.g., altered prosody) have been described in symptomatic Huntington's Disease (HD) individuals, however, the extent to which speech changes in gene positive pre-manifest (PreHD) individuals is largely unknown. The speech of individuals carrying the mutant HTT gene is a behavioural/motor/cognitive marker demonstrating some potential as an objective indicator of early HD onset and disease progression. Speech samples were acquired from 30 individuals carrying the mutant HTT gene (13 PreHD, 17 early stage HD) and 15 matched controls. Participants read a passage, produced a monologue and said the days of the week. Data were analysed acoustically for measures of timing, frequency and intensity. There was a clear effect of group across most acoustic measures, so that speech performance differed in-line with disease progression. Comparisons across groups revealed significant differences between the control and the early stage HD group on measures of timing (e.g., speech rate). Participants carrying the mutant HTT gene presented with slower rates of speech, took longer to say words and produced greater silences between and within words compared to healthy controls. Importantly, speech rate showed a significant correlation to burden of disease scores. The speech of early stage HD differed significantly from controls. The speech of PreHD, although not reaching significance, tended to lie between the performance of controls and early stage HD. This suggests that changes in speech production appear to be developing prior to diagnosis., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Spectral measures are sensitive to dysarthric speech. However, it is unclear whether the spectral differences in dysarthric and healthy speech are due to slow articulation rate or reflect other qualitative changes in speech. Spectral measures were used to detect differences between habitual, slow, and "clear" speaking modes in 12 healthy speakers. Matched t-tests were used to determine differences in the rate and degree of spectral change between the speaking modes. Pearson's correlation coefficients were calculated to assess how well rate of spectral change predicts articulation rate (syllables per second). Clear speech had a significantly higher degree of spectral change than habitual speech, and slow speech had a significantly slower rate of spectral change than habitual and clear speaking modes. These differences occurred in all 12 speakers. The rate of spectral change was correlated with articulation rate across all speakers (range of r = .8-.9 within individual speaking modes) and therefore is a gross predictor of articulation rate. These results suggest that measures of the degree and rate of spectral change together can be used to detect changes between clear, slow, and habitual speaking modes, and hold potential as performance measures.

Hemispherectomy (disconnection or removal of an entire cerebral hemisphere) is a rare surgical procedure used for the relief of drug-resistant epilepsy in children. After hemispherectomy, contralateral hemiplegia persists whereas gross expressive and receptive language functions can be remarkably spared. Motor speech deficits have rarely been examined systematically, thus limiting the accuracy of postoperative prognosis. We describe the speech profiles of hemispherectomized participants characterizing their intelligibility, articulation, phonological speech errors, dysarthric features, and execution and sequencing of orofacial speech and non-speech movements. Thirteen participants who had undergone hemispherectomy (six left, seven right; nine with congenital, four with acquired hemiplegia; operated between four months and 13 years) were investigated. Results showed that all participants were intelligible but showed a mild dysarthric profile characterized by neuromuscular asymmetry and reduced quality and coordination of movements, features that are characteristic of adult-onset unilateral upper motor neuron dysarthria, flaccid-ataxic variant. In addition, one left and four right hemispherectomy cases presented with impaired production of speech and non-speech sequences. No participant showed evidence of verbal or oral dyspraxia. It is concluded that mild dysarthria is persistent after left or right hemispherectomy, irrespective of age at onset of hemiplegia. These results indicate incomplete functional re-organization for the control of fine speech motor movements throughout childhood, and provide no evidence of hemispheric differences., (2010 Elsevier Inc. All rights reserved.)

Lexical-semantic access and retrieval was examined in 15 adults diagnosed with schizophrenia and matched controls. This study extends the literature through the inclusion of multiple examinations of lexical-semantic production within the same patient group and through correlating performance on these tasks with various positive and negative clinical symptoms. On tasks of verbal fluency, meaning generation, sentence production using contextual information and confrontation naming, participants with schizophrenia made significantly more semantic errors on naming tasks; produced fewer meanings for homophones; produced fewer items on semantic, phonological, cued and switching fluency tasks; and produced more errors on sentence production tasks when compared to healthy controls. Significant correlations were also observed between ratings of psychomotor poverty and measures of semantic production and mental inflexibility. This study has provided additional evidence for deficits in lexical-semantic retrieval which are not due to underlying semantic store degradation, do not involve phonological based retrieval, and at the level of sentence generation appear to vary as a function of the contextual constraints provided.