Speech motor profiles in primary progressive aphasia

Purpose: Previous research on motor speech disorders (MSDs) in primary progressive aphasia (PPA) has largely focused on patients with the nonfluent/agrammatic variant of PPA (nfvPPA), with few systematic descriptions of MSDs in variants other than nfvPPA. There has also been an emphasis on studying apraxia of speech, whereas less is known about dysarthria or other forms of MSDs. This study aimed to examine the qualitative and quantitative characteristics of MSDs in a prospective sample of individuals with PPA independent of subtype. Method: We included 38 participants with a root diagnosis of PPA according to current consensus criteria, including one case with primary progressive apraxia of speech. Speech tasks comprised various speech modalities and levels of complexity. Expert raters used a novel protocol for auditory speech analyses covering all major dimensions of speech. Results: Of the participants, 47.4% presented with some form of MSD. Individual speech motor profiles varied widely with respect to the different speech dimensions. Besides apraxia of speech, we observed different dysarthria syndromes, special forms of MSDs (e.g., neurogenic stuttering), and mixed forms. Degrees of severity ranged from mild to severe. We also observed MSDs in patients whose speech and language profiles were incompatible with nfvPPA. Conclusions: The results confirm that MSDs are common in PPA and can manifest in different syndromes. The findings emphasize that future studies of MSDs in PPA should be extended to all clinical variants and should take into account the qualitative characteristics of motor speech dysfunction across speech dimensions

Towards a clinical assessment of acquired speech dyspraxia.

No standardised assessment exists for the recognition and quantification of acquired speech dyspraxia (also called apraxia of speech, AS). This thesis aims to work towards development of such an assessment based on perceptual features. Review of previous features claimed to characterise AS and differentiate it from other acquired pronunciation problems (dysarthrias; phonemic paraphasia - PP) has proved negative. Reasons for this have been explored. A reconceptualisation of AS is attempted based on physical studies of AS, PP and the dysarthrias; their position and relationship within coalitional models of speech production; by comparison with normal action control and other dyspraxias. Contrary to the view of many it is concluded that AS and PP are dyspraxias (albeit different types). However, due to the interactive nature of speech-language production and behaviour of the vocal tract as a functional whole AS is unlikely to be distinguishable in an absolute fashion based on single speech characteristics. Rather it is predicted that pronunciation disordered groups will differ relatively on total error profiles and susceptibility to associated effects (variability; propositionality; struggle; length-complexity; latency-utterance times). Using a prototype battery and refined error transcription and analysis procedures a series of studies test predictions on three groups: spastic dysarthrics (n = 6) AS and PP without (n = 12) and with (n = 12) dysphasia. The main conclusions do not support the error profile hypotheses in any straightforward manner. Length-complexity effects and latency-utterance times fail to consistently separate groups. Variability, propositionality and struggle proved the most reliable indicators. Error profiles remain the closest indicators of speakers' intelligibility and therapeutic goals. The thesis argues for a single case approach to differential diagnosis and alternative statistical analyses to capture individual and group differences. Suggestions for changes to the prototype clinical battery and data management to effect optimal speaker differentiation conclude the work

New perspectives on speech motor planning and programming in the context of the four- level model and its implications for understanding the pathophysiology underlying apraxia of speech and other motor speech disorders

BACKGROUND : The complexity of speech motor control, and the incomplete conceptualisation of phases in the transformation of the speech code from linguistic symbols to a code amenable to a motor system, tend to obscure the understanding of acquired apraxia of speech (AOS). The four-level framework (FLF) of speech sensorimotor control suggests the differentiation between speech motor planning, programming and execution and locate the locus of disruption in AOS in the motor planning phase. Currently, terminological confusion and uncertainty regarding phases in speech motor control still complicate the characterisation of AOS. This neuromotor disorder is inconsistently described in the literature as a “planning or programming”, “planning and programming”, or as a “planning and/or programming” disorder. PURPOSE : To describe a new version of the FLF, the FL (four-level) model, which further explicates and differentiates between speech motor planning, programming, and execution levels or phases of processing; to integrate concepts from computational modelling into the FL model and propose distinct control architectures for both the planning and programming levels; and to identify the loci and nature of disruption in the motor planning phase which could explain the pathophysiology and core features of AOS. DISCUSSION AND CONCLUSIONS : A four-level model is presented that differentiates two pre-execution phases and an execution phase. The first pre-execution phase is controlled by a motor planner and involves an inverse model, an efference copy, and a forward model for each sound or over-learnt utterance. This phase also involves a forward predictive planner which enables the system to handle the planning of several sounds and to plan coarticulation of sounds. The motor planner is operated according to an auxiliary forward model architecture. AOS is depicted as a breakdown at several possible points in the motor planning phase. The second pre-execution phase is driven by a motor program generator and predictive controller that is governed by an integral forward model architecture. The final execution phase is portrayed as being driven by closed loop control. The conceptualization of the programmer challenges the traditional view of execution and not only that of planning as is generally accepted. The implications for the classification of motor speech disorders are discussed. Future research should address the exact nature of articulatory movements and other features of speech across the range of planning, pure programming, programming-execution and pure execution disorders.https://www.tandfonline.com/loi/paph202021-05-21hj2020Speech-Language Pathology and Audiolog

Optimization of acoustic feature extraction from dysarthric speech

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, February 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 171-180).Dysarthria is a motor speech disorder characterized by weak or uncoordinated movements of the speech musculature. While unfamiliar listeners struggle to understand speakers with severe dysarthria, familiar listeners are often able to comprehend with high accuracy. This observation implies that although the speech produced by an individual with dysarthria may appear distorted and unintelligible to the untrained listener, there must be a set of consistent acoustic cues that the familiar communication partner is able to interpret. While dysarthric speech has been characterized both acoustically and perceptually, most accounts tend to compare dysarthric productions to those of healthy controls rather than identify the set of reliable and consistently controlled segmental cues. This work aimed to elucidate possible recognition strategies used by familiar listeners by optimizing a model of human speech recognition, Stevens' Lexical Access from Features (LAFF) framework, for ten individual speakers with dysarthria (SWDs). The LAFF model is rooted in distinctive feature theory, with acoustic landmarks indicating changes in the manner of articulation. The acoustic correlates manifested around landmarks provide the identity to articulator-free (manner) and articulator-bound (place) features.(cont.) SWDs created weaker consonantal landmarks, likely due to an inability to form complete closures in the vocal tract and to fully release consonantal constrictions. Identification of speaker-optimized acoustic correlate sets improved discrimination of each speaker's productions, evidenced by increased sensitivity and specificity. While there was overlap between the types of correlates identified for healthy and dysarthric speakers, using the optimal sets of correlates identified for SWDs adversely impaired discrimination of healthy speech. These results suggest that the combinations of correlates suggested for SWDs were specific to the individual and different from the segmental cues used by healthy individuals. Application of the LAFF model to dysarthric speech has potential clinical utility as a diagnostic tool, highlighting the fine-grain components of speech production that require intervention and quantifying the degree of impairment.by Thomas M. DiCicco, Jr.Ph.D

ACOUSTIC SPEECH MARKERS FOR TRACKING CHANGES IN HYPOKINETIC DYSARTHRIA ASSOCIATED WITH PARKINSON’S DISEASE

Previous research has identified certain overarching features of hypokinetic dysarthria associated with Parkinson’s Disease and found it manifests differently between individuals. Acoustic analysis has often been used to find correlates of perceptual features for differential diagnosis. However, acoustic parameters that are robust for differential diagnosis may not be sensitive to tracking speech changes. Previous longitudinal studies have had limited sample sizes or variable lengths between data collection. This study focused on using acoustic correlates of perceptual features to identify acoustic markers able to track speech changes in people with Parkinson’s Disease (PwPD) over six months. The thesis presents how this study has addressed limitations of previous studies to make a novel contribution to current knowledge. Speech data was collected from 63 PwPD and 47 control speakers using an online podcast software at two time points, six months apart (T1 and T2). Recordings of a standard reading passage, minimal pairs, sustained phonation, and spontaneous speech were collected. Perceptual severity ratings were given by two speech and language therapists for T1 and T2, and acoustic parameters of voice, articulation and prosody were investigated. Two analyses were conducted: a) to identify which acoustic parameters can track perceptual speech changes over time and b) to identify which acoustic parameters can track changes in speech intelligibility over time. An additional attempt was made to identify if these parameters showed group differences for differential diagnosis between PwPD and control speakers at T1 and T2. Results showed that specific acoustic parameters in voice quality, articulation and prosody could differentiate between PwPD and controls, or detect speech changes between T1 and T2, but not both factors. However, specific acoustic parameters within articulation could detect significant group and speech change differences across T1 and T2. The thesis discusses these results, their implications, and the potential for future studies

An investigation of sign dysarthria

This study explores the nature of sign production in individuals with neurogenic movement disorders. The research goals are to broadly define the phenomenon of dysarthria in signed language; to determine whether anything other than the set of articulators involved differentiates it from dysarthria in spoken language; and to delineate the differences between sign dysarthria and apraxia, and between sign dysarthria and disruption of simple limb movements. In the same way that hearing people may exhibit speech dysarthria in the absence of oral apraxia, deaf signers may, in some cases, exhibit sign dysarthria in the absence of higher level ideomotor impairments. Conversely, just as many movement disorders are more apparent in speech than in simple limb movements, sign dysarthria may also arise in the absence of severe impairment of simple movements, such as reaching or pointing. An ancillary question that this research addresses is the establishment of articulatory measures of sign dysarthria, and of normal signing. Findings from this study indicate that dysarthria, as distinct from apraxia, aphasia, and loss of simple movement, does manifest itself in sign language, which suggests that speech motor control research should eschew models of dysarthria framed around specific articulators, in favour of those that emphasize patterns of movement. However, just as dysarthria is not articulator-specific, it is also not fundamentally linguistic in nature. The reason that dysarthria can occur in either a vocal or a manual language modality is because both use very rapid, complex, co-ordinated movements. The movement speed and complexity facilitate the rapid information transfer that is necessary for any linguistic system, but that does not make disruptions to it inherently linguistic. One would predict that subjects with dysarthria would also be impaired at any task with similar motor demands, but since few normal activities require such a high level of movement precision, deficits manifest themselves primarily in speech or sign

Repeated attempts, phonetic errors, and syllabifications in a case study:Evidence of impaired transfer from phonology to articulatory planning

Background: In aphasia, impairments affecting stages after lexical access have been subdivided into three types: 1. impairments specifying a sequence of phonemes after lexical access (the reproduction variety of conduction aphasia, CA); 2. impairments holding on to these representations during articulatory planning (the short-term memory (STM) variety of CA); and 3. Impairments specifying integrated articulatory/motor plans for clusters of phonemes (apraxia of speech, AoS). Models of speech production, however, suggest more articulated possibilities (i.e., different subtypes of articulatory impairments). Aims: We investigated the impairment in a person with aphasia whose preliminary assessment revealed mixed speech characteristics, combining features typically used to identify CA – phonological errors across tasks and repeated attempts at the target – with features typically used to identify AoS – phonetic errors and word dysfluencies (phoneme elongations and syllabifications). Our preliminary hypothesis was that there was a difficulty transferring information from an (intact) phonological output buffer to articulatory planning. Slow/noisy transfer would predict dysfluencies, errors selecting motor programs, but also repeated attempts (RA) at revising the output in the face of intact feedback and intact original representations. This hypothesis also predicts effects of position and phonological complexity. Method and Procedure: We tested CS’s word and nonword repetition, word reading, and picture naming. We quantified lexical and non-lexical errors, repeated attempts, phonetic errors, and syllabifications. We assessed effects of word frequency, word length, phoneme position, and syllabic and phonological complexity. Results: CS made similar errors across tasks, consistent with a post-lexical impairment. His RAs most often built up a correct target from fragments and/or previously incorrect attempts, similar to a conduite d’approche. He also produced more errors in later positions, and more repeated attempts on longer words. However, inconsistent with decay from an output buffer, phonological errors did not increase with word length. Finally, frequency mattered, consistent with easier/faster access to simpler/more practiced motor plans. Conclusions: CS’s speech characteristics and anatomical lesion are consistent with transfer limitations between phonology and articulatory planning. However, CS has more difficulties in computing articulatory plans than in selecting and retaining phonological representations, as commonly attributed to CA. CS’s case suggests that different varieties of phonological and articulatory disorders need to be distinguished, beyond a strict dichotomy AoS/CA (e.g., involving transfer limitations and difficulties in computing, selecting,, and/or initiating articulatory plans)

Does Speech-To-Text Assistive Technology Improve the Written Expression of Students with Traumatic Brain Injury?

Traumatic Brain Injury outcomes vary by individual due to age at the onset of injury, the location of the injury, and the degree to which the deficits appear to be pronounced, among other factors. As an acquired injury to the brain, the neurophysiological consequences are not homogenous; they are as varied as the individuals who experience them. Persistent impairment in executive functions of attention, initiation, planning, organizing, and memory are likely to be present in children with moderate to severe TBIs. Issues with sensory and motor skills, language, auditory or visual sensation changes, and variations in emotional behavior may also be present. Germane to this study, motor dysfunction is a common long-term sequelae of TBI that manifests in academic difficulties. Borrowing from the learning disability literature, children with motor dysfunction are likely to have transcription deficits, or deficits related to the fine-motor production of written language. This study aimed to compare the effects of handwriting with an assistive technology accommodation on the writing performance of three middle school students with TBIs and writing difficulties. The study utilized an alternating treatments design (ATD), comparing the effects of handwriting responses to story prompts to the use of speech-to-text AT to record participant responses. Speech-to-text technology, like Dragon Naturally Speaking converts spoken language into a print format on a computer screen with a high degree of accuracy. In theory, because less effort is spent on transcription, there is a reduction in cognitive load, enabling more time to be spent on generation skills, such as idea development, selecting more complex words that might be otherwise difficult to spell, and grammar. Overall, all three participants showed marked improvement with the application of speech-to-text AT. The results indicate a positive pattern for the AT as an accommodation with these children that have had mild-to-moderate TBIs as compared to their written output without the AT accommodation. The findings of this study are robust. Through visual analysis of the results, it is evident that the speech-to-text dictation condition was far superior to the handwriting condition (HW) with an effect size that ranged + 3.4 to + 8.8 across participants indicating a large treatment effect size. Perhaps more impressive, was 100 percent non-overlap of data between the two conditions across participants and dependent variables. The application of speech-to-text AT resulted in significantly improved performance across writing indicators in these students with a history of TBIs. Speech-to-Text AT may prove to be an excellent accommodation for children with TBI and fine motor skill deficits. The conclusions drawn from the results of this study indicate the Speech-to-Text AT was more effective than a handwriting condition for all three participants. By providing this AT, these students each improved in the quality, construction, and duration of their written expression as evidenced in the significant gains in TWW, WSC, and CWS