Acquired Apraxia Of Speech Research Articles

Speech Intelligibility Outcomes Associated With Treatment for Acquired Apraxia of Speech: Magnitude of Change and Stability of Measurement.

The purpose of this investigation was to examine single-word speech intelligibility outcomes following sound production treatment in a group of 22 speakers with chronic acquired apraxia of speech (AOS) and aphasia. Also, the stability of repeated posttreatment intelligibility measures was examined for two scoring methods. The Assessment of Intelligibility of Dysarthric Speech was administered twice to each participant at pretreatment and twice at 8 weeks posttreatment. The test-retest reliability of the pretreatment samples was evaluated in a prior study; repeated samples were found to be stable over sampling times. For the current study, the three expert listeners who had rated the pretreatment samples scored the posttreatment samples using transcription and multiple-choice scoring formats. An additional expert listener, blinded to sampling time, scored pre- and posttreatment samples. The posttreatment samples were found to be stable over sampling times for the group. Posttreatment intelligibility scores were statistically significantly higher than the pretreatment scores for both scoring methods (i.e., increases of 9%-10%). Scores derived from the two scoring methods were strongly, positively correlated, with multiple-choice scores being significantly higher than transcription. The scoring methods did not differ significantly in the amount of change found from pre- to posttreatment. There were no statistically significant correlations between AOS severity and changes in pre- to posttreatment intelligibility scores. Performance for most participants was similar to group performance. Stability of posttreatment intelligibility samples supports use of intelligibility scores as outcome measures. This group of speakers demonstrated statistically significant increases in single-word speech intelligibility following sound production treatment. https://doi.org/10.23641/asha.26972425.

Stability Over Time of Word Syllable Duration for Speakers With Acquired Apraxia of Speech.

Neurogenic speech and language disorders-such as acquired apraxia of speech (AOS) and aphasia with phonemic paraphasia (APP)-are often misdiagnosed due to similarities in clinical presentation. Word syllable duration (WSD)-a measure of average syllable length in multisyllabic words-serves as a proxy for speech rate, which is an important and arguably more objective clinical characteristic of AOS and APP. This study reports stability of WSD over time for speakers with AOS (and aphasia). Twenty-nine participants with AOS and aphasia (11 women and 18 men, Mage = 53.5 years, SD = 13.3) repeated 30 multisyllabic words (of three-, four-, and five-syllable lengths) on three occasions across 4 weeks. WSDs were calculated for each word and then averaged across each list (i.e., word length), as well as across combined lists (i.e., all 30 words) to yield four WSDs for each participant at each time point. Stability over time was calculated using Friedman's test for the group and using Spearman's rho for the individual level. Effects of time and word length were examined using robust mixed-effects linear regression. Friedman's tests and correlations indicated no significant difference in WSDs across sampling occasions for each word length separately or combined. WSD correlated positively with AOS severity and negatively with intelligibility but was not correlated with aphasia severity. Regression analyses confirmed WSD to be stable over time, while WSD calculated from only five tokens (i.e., WSD-5) was less stable over time. Results indicate that WSD can be a stable measure over time, at the individual and group level, providing support for its use in diagnosis and/or as an outcome measure, both clinically and for research. In general, WSD outperformed WSD-5, suggesting that it may be better to calculate WSD from more than five tokens. Stability of WSD in other populations and suitability for differential diagnosis need to be determined. Currently, differentiating disorders by speaking rate, alone, is not recommended. https://doi.org/10.23641/asha.25438735.

Assessment protocol for acquired apraxia of speech.

To develop an assessment protocol for speech motor planning with phonologically balanced stimuli for Brazilian Portuguese, including all necessary variables for this diagnosis. Three stages were carried out: In the first, word lists were built with the main criterion being syllabic and accentual patterns. From the survey conducted in Stage 1, the words that composed the first version of the protocol lists in Stage 2 were selected, and grouped into two fundamental tasks for diagnosing acquired apraxia of speech (AOS): repetition and Reading Aloud (RA). In Stage 3, the occurrence of words was investigated using the Brazilian Corpus (PUC-SP) - Linguateca database, and a statistical analysis was performed to verify if the repetition and RA lists were balanced in terms of the occurrences. Thus, the lists were distributed in quartiles and submitted to both descriptive and bivariate analyses. A significance level of 5% (p<0.05) was adopted. After completion of all stages, the words that composed the lists of the repetition and RA tasks were obtained. Finally, other tasks considered essential for the assessment of AOS, such as diadochokinetic rates and the board for spontaneous oral emission, were then added to the protocol. The developed protocol contains the tasks considered standard for the assessment of AOS according to the international literature, which makes this instrument important for diagnosing this disorder in speakers of Brazilian Portuguese.

Protocolo de avaliação para apraxia de fala adquirida

ABSTRACT Purpose To develop an assessment protocol for speech motor planning with phonologically balanced stimuli for Brazilian Portuguese, including all necessary variables for this diagnosis. Methods Three stages were carried out: In the first, word lists were built with the main criterion being syllabic and accentual patterns. From the survey conducted in Stage 1, the words that composed the first version of the protocol lists in Stage 2 were selected, and grouped into two fundamental tasks for diagnosing acquired apraxia of speech (AOS): repetition and Reading Aloud (RA). In Stage 3, the occurrence of words was investigated using the Brazilian Corpus (PUC-SP) - Linguateca database, and a statistical analysis was performed to verify if the repetition and RA lists were balanced in terms of the occurrences. Thus, the lists were distributed in quartiles and submitted to both descriptive and bivariate analyses. A significance level of 5% (p&lt;0.05) was adopted. Results After completion of all stages, the words that composed the lists of the repetition and RA tasks were obtained. Finally, other tasks considered essential for the assessment of AOS, such as diadochokinetic rates and the board for spontaneous oral emission, were then added to the protocol. Conclusion The developed protocol contains the tasks considered standard for the assessment of AOS according to the international literature, which makes this instrument important for diagnosing this disorder in speakers of Brazilian Portuguese.

Metalinguistic Awareness as Self-Management in People with Apraxia of Speech and Aphasia: Lived Experience from a Longitudinal Case Series

People with acquired apraxia of speech (AOS) and aphasia commonly experience long-term communication disability without support for their ongoing recovery or self-management. Little is known about their lived experience of metalinguistic abilities and capacity to harness them for self-management of speech production. The author, a speech and language therapist (SLT), revisited her previous qualitative study after her own more recent lived experience of recovering from mild aphasia. Participant perspectives were explored from a longitudinal case series (eleven people with confirmed AOS and aphasia discharged from SLT), with full ethical approval. The anonymized data comprised detailed transcripts from videoed semi-structured interviews, participant assessments, field notes and reflections, member checking, and reflexivity. The original systematic thematic analysis of these data in NVivo software was re-interrogated by the author, deriving three overarching themes: Metalinguistic awareness of spoken communication breakdown, Self-management, and Therapeutic assessment. The participants conveyed the nature, occurrence, context, mechanism, and purpose underlying errors in spoken communication (themes of What, When, Where, How and Why). They generated compensatory strategies, elucidated via subthemes with quotations, verified contemporaneously by an original participant volunteer. The findings support the value of metalinguistic co-construction during in-depth assessments of communication disability, offering fresh avenues for long-term self-management in aphasia and AOS.

A Comparison of Sound Production Treatment and Metrical Pacing Therapy for Apraxia of Speech: A Single-Case Experimental Design.

The purpose of this investigation was to compare the effects of two specific treatment protocols for acquired apraxia of speech (AOS): Sound Production Treatment (SPT) and Metrical Pacing Therapy (MPT), and to examine changes in communicative participation. Four speakers with chronic AOS and aphasia were each administered SPT and MPT in a replicated crossover design (ABACA/ACABA) with nonconcurrent multiple baselines across participants and behaviors. Treatment outcomes were compared with respect to whole word correctness (WWC) for treated and untreated multisyllabic word targets. Speech intelligibility was assessed using the Chapel Hill Multilingual Intelligibility Test, and communicative participation was measured using the Communicative Participation Item Bank at baseline, washout, and follow-up phases. Three of the four participants experienced statistically significant improvements in WWC with SPT, and three of the four participants with MPT. Based on a priori criteria, three participants demonstrated relatively greater benefit from SPT and one participant demonstrated relatively greater benefit from MPT. There were measurable improvements in intelligibility following SPT for three of the four participants. Only one participant in this investigation reported a significant change in communicative participation, and only following MPT. This study demonstrated that individuals in the chronic stages of AOS can benefit from both SPT and MPT, corroborating prior research on articulatory kinematic and rate and/or rhythm control treatment approaches. It contributes a comparison of two protocols for AOS with respect to whole word targets, intelligibility, and individual self-report of communicative participation changes. More participants showed a relative advantage of SPT over MPT. One individual reported communicative participation improvement after MPT. https://doi.org/10.23641/asha.23971929.

Three-Dimensional Speech Profiles in Stroke Aphasia and Apraxia of Speech.

Behaviorally, acquired apraxia of speech (AOS) is a multidimensional syndrome that the experienced clinician recognizes based on impaired articulation and abnormal temporal prosody. We conducted this study to determine the extent to which three core features of AOS-when defined quantitatively-distinguish categorically among aphasia with no or minimal speech sound involvement, aphasia with AOS, and aphasia with phonemic paraphasia (APP). The study involved retrospective analysis of 195 participants with stroke-induced aphasia. We used three quantitative measures (phonemic error frequency, distortion error frequency, and word syllable duration [WSD]) to divide the sample into four participant groups according to the most likely speech diagnosis: aphasia with minimal speech sound errors, AOS, APP, and a borderline group with mixed profiles. We then conducted nonparametric comparisons across groups for which the measures were not defined and visualized all three measures in a three-dimensional graph. The measures distributed as multidimensional spectra rather than discrete diagnostic entities, and there was considerable behavioral overlap among participant groups. Thirty percent of participants presented with aphasia with minimal sound production difficulties, and they were statistically indistinguishable from the APP group on distortion frequency and WSD. Distortion frequency and WSD were in a borderline region between AOS and APP for 29% of participants. Compared to all other groups, participants with AOS produced significantly more errors that affected listeners' phonemic perception. The results suggest that the current AOS-APP dichotomy has limited validity. We conclude that a continuous multidimensional view of speech variation would be a constructive perspective from which to understand how the left cerebral hemisphere produces speech and that quantitative and normed speech measures should be used to inform differential diagnosis in clinical settings. https://doi.org/10.23641/asha.21807609.

Case study: use of sentence completion with a person with aphasia and apraxia of speech

ABSTRACT Several interventions for acquired apraxia of speech (AOS) involve models, imitation, or repetition to elicit production of words. Early researchers wrote about anecdotal experiences, in which sentence completion facilitated speech production for individuals with AOS. The use of sentence completion to elicit production of words during intervention has not been systematically researched. The purpose of this research was to evaluate the effectiveness of sentence completion to elicit correct productions of words, as part of an intervention for one individual with aphasia and AOS. Training occurred three times a week for six weeks. In each session, the participant answered 20 simple questions, for which the answer was one of 20 target words. Ten of these 20 words were used for training, while the other set of 10 words remained untrained. During training, the participant produced words, as the final word of a sentence. The participant improved production of the trained target words. By the end of training, the participant produced more words, as the final word in a sentence and as the answer to a simple question. For this case study, an individual with severe Broca’s aphasia and severe AOS increased the number of personally-relevant words produced following training using sentence completion to elicit production.

Generalization outcomes of Sound Production Treatment (SPT) for acquired apraxia of speech: relationship to treatment dosage

ABSTRACT Background Dosage is an important aspect of treatment for acquired apraxia of speech (AOS) that has received little attention. Knowledge concerning the association of dosage to treatment outcomes is crucial for informing clinical practice and treatment research. Dosage metrics, representing the number of treatment sessions and teaching episodes (TEs) required to achieve specific performance milestones with Sound Production Treatment (SPT), have recently been provided for treated items. Aims The current investigation was designed to extend AOS dosage research to untreated items. Methods and Procedures Retrospective analyses were performed using data from a previously reported SPT study (Wambaugh et al., 2017) in which 20 speakers with AOS received two applications of SPT with different practice schedules (i.e., SPT-Random and SPT-Blocked). Probe data were used to determine achievement of the following milestones: 1) change above baseline; 2) clinically relevant improvement; and 3) mastery. Follow-up data were used to examine the relationship between the dosage metrics and maintenance of accuracy. Outcomes and Results On average, change above baseline and clinically relevant improvement was achieved for untreated items following 9–10 and 7–8 treatment sessions, respectively. Mastery of untreated items occurred for 45% of targets, following an average of 16–17 treatment sessions. TEs varied widely for all dosage metrics. No statistically significant differences were found between practice schedules for any of the dosage metrics. Better maintenance was associated with earlier achievement of performance milestones. More treatment sessions and TEs were required to meet performance milestones for untreated items in comparison to treated items. Conclusions This study provides dosage metrics for response generalization outcomes which can be used for planning and guiding treatment for AOS.

Effects of Verb Network Strengthening Treatment on Sound-Level and Speech Production Errors in Individuals With Aphasia and Acquired Apraxia of Speech.

Purpose This retrospective pilot study investigated whether sound-level and speech production errors decreased in confrontation naming following Verb Network Strengthening Treatment (VNeST) for four participants with acquired apraxia of speech (A-AOS) and aphasia for whom lexical retrieval was previously reported. Specifically, we investigated a potential increase in correct number of syllables per word and posttreatment changes across three domains of speech: segmental production, fluency, and prosody. It was hypothesized that treatment shown to increase lexical retrieval in persons with aphasia and A-AOS could potentially facilitate a reduction in sound-level and speech production errors consistent with dual diagnoses of A-AOS and aphasia. Method Naming responses from four participants with aphasia and A-AOS who previously participated in VNeST studies were investigated for correct number of syllables per word and measures of segmental speech, fluency, and prosody. Results Significant gains in at least one measure of speech production were reported for three of the participants. One participant demonstrated decreased segmental speech errors, two showed significant reduction on syllable segmentation, and two demonstrated a significant reduction on false starts and pauses. Significant gains in production of correct number of syllables were limited to one participant, and one participant did not demonstrate increased accuracy on any measure of speech production. Conclusions While speech production errors consistent with motor speech impairment cannot always be definitively distinguished from the confound of aphasia, two participants produced significantly decreased segmentation of syllables, a characteristic unique to A-AOS. The sound-level and speech production changes recorded may be attributed to a combination of interacting motor and language processes and resource allocation. In addition, specific components of VNeST may have contributed to speech production changes. Future work will focus on a prospective study of effects of language therapy (e.g., VNeST) on measures of speech production with investigation beyond the single-word level.

Differential Diagnosis of Apraxia of Speech in Children and Adults: A Scoping Review.

Purpose Despite having distinct etiologies, acquired apraxia of speech (AOS) and childhood apraxia of speech (CAS) share the same central diagnostic challenge (i.e., isolating markers specific to an impairment in speech motor planning/programming). The purpose of this review was to evaluate and compare the state of the evidence on approaches to differential diagnosis for AOS and CAS and to identify gaps in each literature that could provide directions for future research aimed to improve clinical diagnosis of these disorders. Method We conducted a scoping review of literature published between 1997 and 2019, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. For both AOS and CAS, literature was charted and summarized around four main methodological approaches to diagnosis: speech symptoms, quantitative speech measures, impaired linguistic-motor processes, and neuroimaging. Results Results showed that similar methodological approaches have been used to study differential diagnosis of apraxia of speech in adults and children; however, the specific measures that have received the most research attention differ between AOS and CAS. Several promising candidate markers for AOS and CAS have been identified; however, few studies report metrics that can be used to assess their diagnostic accuracy. Conclusions Over the past two decades, there has been a proliferation of research identifying potential diagnostic markers of AOS and CAS. In order to improve clinical diagnosis of AOS and CAS, there is a need for studies testing the diagnostic accuracy of multiple candidate markers, better control over language impairment comorbidity, more inclusion of speech-disordered control groups, and an increased focus on translational work moving toward clinical implementation of promising measures.

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

ABSTRACT 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.

Autonomy-supportive treatment for acquired apraxia of speech: feasibility and therapeutic effect

ABSTRACT Background: Most treatments for acquired apraxia of speech (AOS) rely on clinician-controlled practice conditions and repeated exposure to unimpaired speaker models. Recent motor learning research indicates that autonomy-support, expectation of competence, and external attentional focus may be more beneficial for motivation and skill learning. Aims: We evaluated the feasibility and basic therapeutic effect for the initial phase of a new speech production treatment program, ActionSC, that uses self-modeling and clinician coaching to help learners with AOS build their own practice program. Methods and Procedures: The single participant was a woman with moderate AOS and nonfluent aphasia. She met with project staff twice per week to review practice strategies, develop and adjust self-modeled video cues, work on her speech, and monitor progress. The program was structured around a custom app installed on a tablet computer. Most practice was directed by the participant based on options provided by the treating clinician. We used a multiple baseline across behavior design to evaluate the relationship between this treatment and oral reading probe performance for 30 conversational phrases the participant wanted to learn to say. Outcomes and Results: Experimental control was demonstrated, with target phrases remaining at baseline levels, then improving at the time treatment was introduced sequentially across three conversation topics. Effect sizes were moderate to large after 9–12 therapy sessions plus independent home practice. The participant assumed an active role in evaluating her own performance, administering and adjusting cues, and organizing her home practice. Conclusions: An autonomy-supportive and confidence-building format for speech practice can be feasible and effective for people with AOS. Fixed cueing hierarchies, augmented feedback, and attentional focus on speech movements may be less important in AOS treatment than previously thought. In addition to replicating our preliminary results with other participants and circumstances, there is a need to extend treatment development to later learning phases in order to promote positive change in real-life settings.

Reliability and stability of the metrical stress effect on segmental production accuracy in persons with apraxia of speech.

Acquired apraxia of speech (AOS) involves speech-production deficits on both the segmental and suprasegmental levels. Recent research has identified a non-linear interaction between the metrical structure of bisyllabic words and word-production accuracy in German speakers with AOS, with trochaic words (strong-weak stress) being resistant to errors compared with iambic words (weak-strong). To replicate previous findings in English speakers with AOS, to measure the test-retest reliability of the effect, and to examine the potential impact of different methods of word scoring. Speech samples were collected from 27 speakers with AOS and aphasia. Participants were at least 12 months post-stroke or penetrating brain injury, and represented a large range of AOS and aphasia severities. Productions were elicited via verbal model. Sampling was conducted on three separate occasions: the initial data-collection session and then repeated samplings at 1- and 4-week intervals. Bisyllabic words with a CVCVC segmental structure were selected. The list was divided into sublists representing differing lexical stress patterns: A list of 42 trochees, and one of 37 iambs. All speech samples were phonetically transcribed and then aligned with canonical transcriptions via an edit distance algorithm that followed transcription alignment principles. Phonetic-level errors (distortions) were penalized less severely than phonemic-level errors. Per cent consonants correct and whole-word accuracy were also examined. Trochee and iamb lists were analysed separately. Paired samples t-tests indicated that the modified edit distance was significantly lower for the trochee lists than for the iamb lists. There was a lack of a significant effect of time on the absolute difference between modified edit distance for both lists. Intraclass coefficients suggested the list and procedures used are appropriate as an outcome measure for group research. The results suggest that in English, as in German, the trochaic structure is more resistant to segmental errors in persons with AOS and aphasia, providing replication of the findings of Aichert etal. in 2016. Further, this effect is stable over repeated sampling occasions. Implications for clinical management of AOS include possible ways to scaffold item difficulty and potentially improve stimulus generalization.

Use of diverse diagnostic criteria for acquired apraxia of speech: a scoping review.

There is a growing body of evidence that speech and language therapy (SLT) intervention is effective in improving communication ability for individuals with non-progressive acquired apraxia of speech (AOS). However, there is no universally agreed diagnostic standard for AOS, and diverging opinions on its diagnostic features. This has led to claims that diverse diagnostic criteria may be used to select participants for AOS research studies. These claims raise concerns for evidence-based practice in AOS but have yet to be systematically investigated. To determine the presence, nature and extent of diversity in the diagnostic criteria for non-progressive AOS used in both published studies and clinical practice internationally. The study used a scoping review methodology that followed the 2005 framework of Arksey and O'Malley and included a consultation exercise in the form of an online survey of international SLTs. The scoping review included 157 studies involving participants with acquired AOS, published between 1997 and 2017. There were 264 respondents to the online survey of SLTs, with a completion rate of 72%. Respondents came from 15 countries and had varying levels of clinical experience. This study found that no common set of diagnostic criteria for AOS was used universally across research and practice. Although the diagnostic criteria used to select participants with AOS were reported explicitly in most studies, they varied from study to study. Some studies used directly conflicting criteria. Use of specific diagnostic criteria in studies was influenced by year of publication but not by location. There was a trend towards increasing consistency in diagnostic criteria in recent years. Compared with the research, the survey revealed relatively greater consistency among SLTs on the speech features considered indicative of AOS, although the SLTs who responded to the survey showed variation in how diagnostic criteria were combined into sets. Use of specific diagnostic criteria was not associated with SLTs' location or experience. There were differences between the diagnostic criteria for AOS used most commonly in research studies and those selected most commonly by SLTs in the survey. These findings have implications for the generalizability of AOS research to clinical practice, as well as implications for effective research synthesis. The claim that research and practice in the field of AOS is characterized by the use of diverse diagnostic criteria is supported by this scoping review. The findings support the need to develop a universal consensus standard for AOS diagnosis to ensure consistency across research and clinical practice.

How do persons with apraxia of speech deal with morphological stress in Spanish? A preliminary study

ABSTRACT Equal stress across adjacent syllables and extended syllable durations are amongst the most salient features of acquired Apraxia of Speech (AOS). Most studies conclude that there is a deficit in durational cue processing, whereas the other acoustic stress correlates remain relatively unimpaired. Spanish is a free-stress language in which stress patterns are contrastive, especially in verbal forms (e.g. lavo /ˈlabo/ ‘[I] wash’ vs lavó /laˈbo/ ‘[He/she] washed’). The aim of this preliminary study is to determine whether persons with AOS are able to make the intended stress pattern identifiable and, if so, to determine which acoustic cues they use to avoid the ‘equal stress’ phenomenon. The results show that, for each parameter considered (duration, intensity, fundamental frequency), apraxic participants’ productions differed from those of controls to varying degrees depending on the task. However, 91.7% of the apraxic participants’ realisations were perceived as corresponding to the intended tense and person. These results are interpreted as deriving from a motoric deficit affecting morphological stress processing by subjects with AOS combined with an idiosyncratic compensatory use of the stress cues in order to avoid ‘equal stress’.

Sound Distortion Errors in Aphasia With Apraxia of Speech.

Purpose Loosely defined diagnostic criteria for acquired apraxia of speech (AOS) limit clinicians' ability to diagnose the disorder validly and reliably. The purpose of this study was to contribute to the development of more precise diagnostic guidelines by characterizing the frequency and quality of sound distortion errors in speakers with clinically diagnosed AOS. Method Audio-recorded motor speech evaluations from 24 speakers with AOS and aphasia were analyzed by trained listeners using a narrow phonetic transcription protocol that included 12 distortion categories. We calculated percentage of segments transcribed with phonemic error, distortion error, and a combination of phonemic and distortion error. Results Distortion frequency varied substantially across participants, distributing on a continuum from 5% to 22% of segments. The frequency of phonemic errors was significantly greater than the frequency of distortion errors, which, in turn, was greater than the frequency of distorted substitution errors. The most common distortion qualities were voicing ambiguity and segment lengthening, but over 40% of distortion errors were distributed across an assortment of tongue modifications. Conclusions The results replicated observations from previous studies of speakers with quantitatively defined AOS in a new sample of participants with clinically diagnosed AOS. Similar distortion qualities were observed across studies, offering focus for diagnosticians and guidance for operationalizing future measures. The broad performance continua we observed help explain why binary classification of the presence/absence of AOS can be challenging and indicate a need to develop quantitative norms.

An Investigation of Compensation and Adaptation to Auditory Perturbations in Individuals With Acquired Apraxia of Speech.

Two auditory perturbation experiments were used to investigate the integrity of neural circuits responsible for speech sensorimotor adaptation in acquired apraxia of speech (AOS). This has implications for understanding the nature of AOS as well as normal speech motor control. Two experiments were conducted. In Experiment 1, compensatory responses to unpredictable fundamental frequency (F0) perturbations during vocalization were investigated in healthy older adults and adults with acquired AOS plus aphasia. F0 perturbation involved upward and downward 100-cent shifts versus no shift, in equal proportion, during 2 s vocalizations of the vowel /a/. In Experiment 2, adaptive responses to sustained first formant (F1) perturbations during speech were investigated in healthy older adults, adults with AOS and adults with aphasia only (APH). The F1 protocol involved production of the vowel /ε/ in four consonant-vowel words of Australian English (pear, bear, care, dare), and one control word with a different vowel (paw). An unperturbed Baseline phase was followed by a gradual Ramp to a 30% upward F1 shift stimulating a compensatory response, a Hold phase where the perturbation was repeatedly presented with alternating blocks of masking trials to probe adaptation, and an End phase with masking trials only to measure persistence of any adaptation. AOS participants showed normal compensation to unexpected F0 perturbations, indicating that auditory feedback control of low-level, non-segmental parameters is intact. Furthermore, individuals with AOS displayed an adaptive response to sustained F1 perturbations, but age-matched controls and APH participants did not. These findings suggest that older healthy adults may have less plastic motor programs that resist modification based on sensory feedback, whereas individuals with AOS have less well-established and more malleable motor programs due to damage from stroke.

Error Consistency in Acquired Apraxia of Speech With Aphasia: Effects of the Analysis Unit.

Diagnostic recommendations for acquired apraxia of speech (AOS) have been contradictory concerning whether speech sound errors are consistent or variable. Studies have reported divergent findings that, on face value, could argue either for or against error consistency as a diagnostic criterion. The purpose of this study was to explain discrepancies in error consistency results based on the unit of analysis (segment, syllable, or word) to help determine which diagnostic recommendation is most appropriate. We analyzed speech samples from 14 left-hemisphere stroke survivors with clinical diagnoses of AOS and aphasia. Each participant produced 3 multisyllabic words 5 times in succession. Broad phonetic transcriptions of these productions were coded for consistency of error location and type using the word and its constituent syllables and sound segments as units of analysis. Consistency of error type varied systematically with the unit of analysis, showing progressively greater consistency as the analysis unit changed from the word to the syllable and then to the sound segment. Consistency of error location varied considerably across participants and correlated positively with error frequency. Low to moderate consistency of error type at the word level confirms original diagnostic accounts of speech output and sound errors in AOS as variable in form. Moderate to high error type consistency at the syllable and sound levels indicate that phonetic error patterns are present. The results are complementary and logically compatible with each other and with the literature.

Acquired Apraxia of Speech: The Relationship Between Awareness of Errors in Word Productions and Treatment Outcomes.

Awareness of errors has been considered a clinical feature of acquired apraxia of speech (AOS). However, there is limited research examining error awareness in speakers with AOS. The purpose of this investigation was to examine awareness of errors and explore the relationship between awareness of errors and treatment outcomes in speakers with AOS. Twenty speakers with AOS and aphasia produced mono- and multisyllabic words in a repetition task. Following each production, speakers were asked to judge the accuracy of their production (i.e., correct or incorrect). Then, speakers received Sound Production Treatment. Judgment accuracy of productions for the group ranged from 20% to 96%. There was a weak relationship between judgment accuracy and probe performance at posttreatment (r = .47) and a moderate relationship between judgment accuracy and probe performance at follow-up (r = .53). Findings indicate that speakers with AOS varied in their ability to judge the accuracy of their productions. For some speakers, the ability to judge the accuracy of their productions did not coincide with their production accuracy of treatment stimuli at posttreatment and at follow-up. Further research is needed to explore the relationship between error awareness and treatment outcomes.