Audio-visual matching of speech and non-speech oral gestures in patients with aphasia and apraxia of speech

BACKGROUND: Audio-visual speech perception mechanisms provide evidence for a supra-modal nature of phonological representations, and a link of these mechanisms to motor representations of speech has been postulated. This leads to the question if aphasic patients and patients with apraxia of speech are able to exploit the visual signal in speech perception and if implicit knowledge of audio-visual relationships is preserved in these patients. Moreover, it is unknown if the audio-visual processing of mouth movements has a specific organisation in the speech as compared to the non-speech domain. METHODS: A discrimination task with speech and non-speech stimuli was applied in four presentation modes: auditory, visual, bimodal and cross-modal. We investigated 14 healthy persons and 14 patients with aphasia and/or apraxia of speech. RESULTS: Patients made substantially more errors than normal subjects on both the speech and the non-speech stimuli, in all presentation modalities. Normal controls made only few errors on the speech stimuli, regardless of the presentation mode, but had a high between-subject variability in the cross-modal matching of non-speech stimuli. The patients' cross-modal processing of non-speech stimuli was mainly predicted by lower face apraxia scores, while their audio-visual matching of syllables was predicted by word repetition abilities and the presence of apraxia of speech. CONCLUSIONS: (1) Impaired speech perception in aphasia is located at a supra-modal representational level. (2) Audio-visual processing is different for speech and non-speech oral gestures. (3) Audio-visual matching abilities in patients with left-hemisphere lesions depend on their speech and non-speech motor abilities.     

Voice onset time in aphasia,apraxia of speech and dysarthria: a review

Voice onset time (VOT) is an objective temporal acoustic parameter defined as the time between the release of the oral constriction for plosive production and the onset of vocal fold vibrations. Many researchers consider VOT to be the most reliable acoustic cue for the distinction between voiced and voiceless stops. Previous studies have explored the physiological and linguistic factors underlying VOT production in normal speakers across several languages. A major clinical goal of acoustic analysis in speech disorder is to establish a correlation between the acoustic abnormalities and the phonetic perturbations. VOT could thus be used as an acoustic parameter that indicates the phonetic contrast between voiced and voiceless stops. This paper includes a critical review of the measurement of VOT, factors of VOT variability and the effect of neurogenic communication disorders on VOT. We review the VOT data from subjects who exhibit aphasia, apraxia of speech and dysarthria. These studies reveal that VOT perturbations in aphasia have been interpreted as phonemic or phonetic errors, while VOT abnormalities in apraxia of speech and dysarthria grossly reflect loss of motor control.     

A speech motor learning approach to treating apraxia of speech: Rationale and effects of intervention with an adult with acquired apraxia of speech

Background: In this paper the rationale for a treatment of apraxia of speech, the speech motor learning (SML) approach, is described and the effects of its application explored. The SML approach endeavours to address the underlying inability to plan and program the production of different speech motor targets (SMTs) in changing phonetic contexts and in utterances exceeding a single word/nonword in length.

Aims: The aims of the study were to determine (1) if treatment effects generalised to untreated nonwords and untreated real words with trained vowels and consonants, (2) if a learning effect was maintained, (3) if the treatment task hierarchy of the SML approach could be confirmed, and (4) if the number of speech errors judged perceptually declined across the treatment period on treated and untreated stages.

Methods & Procedures: A multiple baseline single-participant design across behaviours and contexts was used to assess the effects of treatment with a speaker with chronic pure AOS. The first six stages of an eleven-stage treatment hierarchy were consecutively treated. The last five remained untreated.

Outcomes & Results: During treatment, production of untrained nonwords and words containing trained and untrained SMTs improved. For three treated stages the improvement was greater during the treatment phase than during baseline, for words, nonwords, or both. Stage 4 vowels only improved once treatment commenced. Untreated consonant clusters of Stage 10 improved negligibly. Improvement was maintained 2 years post-treatment. The number of speech errors decreased across the treatment period.

Conclusions: Preliminary evidence is provided supporting a general improvement in speech motor planning and programming ability for this participant. The relative value of components of the SML approach needs to be verified in future.     

An acoustic measure of lexical stress differentiates aphasia and aphasia plus apraxia of speech after stroke

Background: Apraxia of Speech (AOS) is partly characterised by impaired production of prosody in words and sentences. Identification of dysprosody is based on perceptual judgements of clinicians, with limited literature on potential quantitative objective measures.

Aims: This study investigated whether an acoustic measure quantifying degree of lexical stress contrastiveness in three syllable words, produced in isolation and in a carrier sentence, differentiated individuals with AOS with/without aphasia (AOS), aphasia only (APH), and healthy controls (CTL).

Methods & Procedures: Eight individuals with aphasia, nine with AOS plus aphasia and 8 age-matched control participants named pictures of strong–weak and weak–strong polysyllabic words in isolation and in a declarative carrier sentence. Pairwise Variability Indices (PVI) were used to measure the normalised relative vowel duration and peak intensity over the first two syllables of the polysyllabic words.

Outcomes & Results: Individuals with aphasia performed similarly to control participants in all conditions. AOS participants demonstrated significantly lower PVI_vowel duration values for words with weak–strong stress produced in the sentence condition only, compared to controls and individuals with aphasia. This was primarily due to disproportionately long vowels in the word-initial weak syllable for AOS participants. There was no difference among groups on PVI_intensity.

Conclusions: The finding of reduced lexical stress contrastiveness for weak–strong words in sentences for individuals with mild to moderate–severe AOS is consistent with the perceptual diagnostic feature of equal stress in AOS. Findings provide support for use of the objective PVI_vowel duration measure to help differentiate individuals with AOS (with/without aphasia), from those with aphasia only. Future research is warranted to explore the utility of this acoustic measure, and others, for reliable diagnosis of AOS.     

A case of crossed aphasia with apraxia of speech

Apraxia of speech (AOS) is a rare, but well-defined motor speech disorder. It is characterized by irregular articulatory errors, attempts of self-correction and persistent prosodic abnormalities. Similar to aphasia, AOS is also localized to the dominant cerebral hemisphere. We report a case of Crossed Aphasia with AOS in a 48-year-old right-handed man due to an ischemic infarct in right cerebral hemisphere.     

Comparing monitoring and production based approaches to the treatment of phonological assembly difficulties in aphasia

Background: Waldron, Whitworth, and Howard (2011 Waldron, H., Whitworth, A. and Howard, D. 2011. Therapy for phonological assembly difficulties: A case series. Aphasiology, 25(4): 434–455. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) replicated the auditory and monitoring therapy reported in a single case by Franklin, Buerk, and Howard (2002 Franklin, S., Buerk, F. and Howard, D. 2002. Generalised improvement in speech production for a subject with reproduction conduction aphasia. Aphasiology, 16(10/11): 1087–1114. [Taylor & Francis Online] , [Google Scholar]) with four participants with phonological assembly difficulties. No participant responded in the same way as Franklin et al.’s client MB and, notably, all improvements seen were item-specific, in contrast to MB who had shown generalised improvements in naming, repetition, and reading aloud. Waldron et al. attributed this difference to the combination of underlying impairments in their participants, in particular additional lexical deficits; it remains unknown whether Franklin et al.’s results would be replicated in someone with a more pure phonological assembly difficulty. It is also unknown whether a more direct therapy approach, targeting a reduction in the production of phonological errors, rather than improving monitoring, might also be effective with this client group.

Aims: The current study aimed to compare the effectiveness of the auditory and monitoring therapy reported by Franklin et al. (2002 Franklin, S., Buerk, F. and Howard, D. 2002. Generalised improvement in speech production for a subject with reproduction conduction aphasia. Aphasiology, 16(10/11): 1087–1114. [Taylor & Francis Online] , [Google Scholar]) with a production-focused therapy based on the articulatory kinematic treatment of apraxia of speech (AOS), in a single participant with phonological assembly difficulties.

Methods & Procedures: Participant RE received three consecutive therapy phases: Franklin et al.’s auditory therapy, followed by a new production therapy involving a hierarchy of articulatory kinematic cues and the production of minimal contrast pairs, and finally Franklin et al.’s monitoring therapy. As RE's linguistic profile was similar to that of Franklin et al.’s client, it was predicted that he would make similar gains, i.e., generalised improvement in the production of treated and untreated words, following all three therapy types.

Outcomes & Results: RE's naming of treated items improved significantly after both the production therapy and the monitoring therapy, but naming of untreated items did not improve and there were no naming improvements following the auditory therapy.

Conclusions: Two possible reasons why RE did not respond as predicted are discussed. First, that RE may have had additional lexical retrieval difficulties, in which case therapy could have improved the link between semantics and lexical phonology; and second, that RE may have had additional mild AOS, in which case therapy may have resulted in improved motor planning abilities. Neither of these hypotheses could fully account for all of RE's results. Nonetheless, the production therapy was shown to be an effective alternative approach for clients with phonological assembly difficulties, when a direct focus on speech production is needed.     

Single-word intelligibility testing in aphasia: Alternate forms reliability,phonetic complexity and word frequency

Background: We recently constructed a single-word speech intelligibility test intended to quantify magnitude of speech sound impairment in individuals with aphasia. To minimise listener learning and strategising, the test included a large set of possible (alternate) test forms and was constructed with high and diverse phonologic similarity among candidate words. Although the corpus was limited in phonetic complexity to single syllables, and although criteria for minimal word frequency were applied, it is possible that more fine-grained differences in phonetic complexity and/or word frequency may introduce varying levels of difficulty across alternate test forms and that reliability, therefore, may be compromised.

Aims: The dual purposes of this study were to evaluate alternate forms reliability for the new intelligibility test and to determine whether word frequency and/or phonetic complexity affected word identification scores.

Methods & Procedures: All words in the 600-word test corpus were coded for overall phonetic complexity and for frequency of occurrence in spoken English. Fifty-one versions of the target 50-word test were generated from this corpus by following designated pseudo-random selection procedures. Speech samples were collected from 13 speakers with aphasia, who each repeated three or four of these 50-word sets. Ten normal-hearing listeners were asked to indicate the words they thought the speakers were trying to say. Per cent accuracy was computed for each speaker, test form and target word.

Outcomes & Results: The intra-class correlation within speakers was 0.97, indicating that the scores across alternate forms were highly reproducible. Analyses at the word level showed that both phonetic complexity and word frequency affected identification accuracy. The effects were seen in almost all participants whose intelligibility scores were in the impaired range.

Conclusions: High frequency of occurrence and low phonetic complexity increase repetition accuracy for individuals with moderate to severe sound production difficulties and aphasia. However, the pseudo-random word selection in the examined word intelligibility test was sufficient to ensure strong alternate forms reliability. Further constraints on the word selection process for this test are not warranted.     

Speech motor control in fluent and dysfluent speech production of an individual with apraxia of speech and Broca's aphasia

Apraxia of speech (AOS) is typically described as a motor‐speech disorder with clinically well‐defined symptoms, but without a clear understanding of the underlying problems in motor control. A number of studies have compared the speech of subjects with AOS to the fluent speech of controls, but only a few have included speech movement data and if so, this was primarily restricted to the study of single articulators. If AOS reflects a basic neuromotor dysfunction, this should somehow be evident in the production of both dysfluent and perceptually fluent speech. The current study compared motor control strategies for the production of perceptually fluent speech between a young woman with apraxia of speech (AOS) and Broca's aphasia and a group of age‐matched control speakers using concepts and tools from articulation‐based theories. In addition, to examine the potential role of specific movement variables on gestural coordination, a second part of this study involved a comparison of fluent and dysfluent speech samples from the speaker with AOS. Movement data from the lips, jaw and tongue were acquired using the AG‐100 EMMA system during the reiterated production of multisyllabic nonwords. The findings indicated that although in general kinematic parameters of fluent speech were similar in the subject with AOS and Broca's aphasia to those of the age‐matched controls, speech task‐related differences were observed in upper lip movements and lip coordination. The comparison between fluent and dysfluent speech characteristics suggested that fluent speech was achieved through the use of specific motor control strategies, highlighting the potential association between the stability of coordinative patterns and movement range, as described in Coordination Dynamics theory.     

Segmental and prosodic variability on repeated polysyllabic word production in acquired apraxia of speech plus aphasia

Background: McNeil and colleagues argued that individuals with pure apraxia of speech (AOS) have low variability of speech error type and error location within repeated multisyllabic words, compared to individuals with conduction aphasia. While this concept has been challenged, subsequent studies have varied in the stimuli and tasks used.

Aims: Our aim was to re-examine the variability of segmental errors, as well as lexical prosodic errors, using the same stimuli and tasks as used by McNeil and colleagues in a sample of individuals with AOS plus aphasia or aphasia alone. This sample is considered to be clinically relevant given the high concomitance of these disorders.

Methods & Procedures: Participants were 20 individuals with stroke-related AOS plus aphasia and 21 with aphasia alone (APH), with diagnosis based on expert judgments using published criteria. Three consecutive repetitions of 10 polysyllabic words were elicited and variability of error type, error location, and durational stress contrast was measured.

Outcome & Results: Errors were significantly more variable in type and more consistent in location within word for the AOS group than the APH group. The AOS group showed a greater number of errors overall, were less likely to improve production over the three repetition trials, and produced no clear difference in vowel duration across the first two syllables (i.e., durational stress contrast) across repetitions. The measure of durational stress contrast was a stronger predictor of AOS presence than the measures of error variability.

Conclusions: The divergence of our findings from previous work likely reflects the more complex profile of the AOS plus aphasia cases in the current study. While durational stress contrast was sufficient to predict diagnostic group, error variability measures were significantly associated with AOS and can contribute to developing targeted intervention goals.     

Whole-exome sequencing supports genetic heterogeneity in childhood apraxia of speech

Background

Childhood apraxia of speech (CAS) is a rare, severe, persistent pediatric motor speech disorder with associated deficits in sensorimotor, cognitive, language, learning and affective processes. Among other neurogenetic origins, CAS is the disorder segregating with a mutation in FOXP2 in a widely studied, multigenerational London family. We report the first whole-exome sequencing (WES) findings from a cohort of 10 unrelated participants, ages 3 to 19 years, with well-characterized CAS.

Methods

As part of a larger study of children and youth with motor speech sound disorders, 32 participants were classified as positive for CAS on the basis of a behavioral classification marker using auditory-perceptual and acoustic methods that quantify the competence, precision and stability of a speaker’s speech, prosody and voice. WES of 10 randomly selected participants was completed using the Illumina Genome Analyzer IIx Sequencing System. Image analysis, base calling, demultiplexing, read mapping, and variant calling were performed using Illumina software. Software developed in-house was used for variant annotation, prioritization and interpretation to identify those variants likely to be deleterious to neurodevelopmental substrates of speech-language development.

Results

Among potentially deleterious variants, clinically reportable findings of interest occurred on a total of five chromosomes (Chr3, Chr6, Chr7, Chr9 and Chr17), which included six genes either strongly associated with CAS (FOXP1 and CNTNAP2) or associated with disorders with phenotypes overlapping CAS (ATP13A4, CNTNAP1, KIAA0319 and SETX). A total of 8 (80%) of the 10 participants had clinically reportable variants in one or two of the six genes, with variants in ATP13A4, KIAA0319 and CNTNAP2 being the most prevalent.

Conclusions

Similar to the results reported in emerging WES studies of other complex neurodevelopmental disorders, our findings from this first WES study of CAS are interpreted as support for heterogeneous genetic origins of this pediatric motor speech disorder with multiple genes, pathways and complex interactions. We also submit that our findings illustrate the potential use of WES for both gene identification and case-by-case clinical diagnostics in pediatric motor speech disorders.     

Treating apraxia of speech (AOS) with EMA-supplied visual augmented feedback

Background: Previous studies have suggested that visual augmented feedback provided by electromagnetic articulography (EMA) helps persons with apraxia of speech (AOS) recover speech motor control following stroke (e.g., Katz et al., 2007 Katz, W., Garst, D., Carter, G., McNeil, M., Fossett, T.Doyle, P. 2007. Treatment of an individual with aphasia and apraxia of speech using EMA visually augmented feedback. Brain and Language, 103: 213–214. [Crossref], [Web of Science ®] , [Google Scholar]). However, the data are few, both in terms of the variety of participants and the speech motor targets investigated.

Aims: This study was designed to determine whether EMA supplied feedback improves articulatory accuracy in an adult with acquired AOS. We also examined whether reduced feedback frequency results in (1) decreased performance during acquisition and (2) enhanced maintenance and generalisation of the targeted behaviours.

Methods & Procedures: A multiple-baseline across-behaviours design was used to assess the efficacy of this treatment for an individual with AOS. Over a 27-week period, the participant received visual feedback provided by an EMA system for treatment of three groups of speech motor targets (SMTs): /j/, /θ/, and /t∫ / with various following VCs. The consonant clusters /br/ and /sw/ served as untreated controls. Frequency of feedback scheduling was 100% for /j/ and /t∫?/, and 50% for /θ/.

Outcomes & Results: For the first group of SMTs treated, /j/, there was acquisition for 4/5 trained words. These were maintained post-treatment and at the long-term probe. Improved performance and maintenance were also noted for 5/8 untreated stimuli, with maintenance shown for most of these words by 1 month post-treatment. The next treated SMT, /θ/, showed acquisition for all five treated items. Two of these five targets were maintained one month post-treatment. All three untreated /θ/ probes showed generalisation, with two of these showing maintenance post-treatment. The third treated group of SMTs, /t∫/, showed improved performance for all of the five treated words. However, these gains could only be attributed to /t∫/ treatment for three of the five words. Two treated items appeared well maintained at 1 month post-treatment. Generalisation and maintenance were also noted for all six untreated /t∫?/ words. However, generalisation from previously treated /j/ and /t∫/ targets was involved in their improved performance. The untrained (control) word data suggested that the gains noted for treated items did not result from across-the-board improvement or unassisted recovery. There were no consistent differences corresponding with low- versus high-frequency feedback conditions.

Conclusions: Augmented kinematic feedback provided by an EMA system improved production for some, but not all, treated targets. Generalisation to untreated probes was also evident. Predictions concerning the effects of feedback frequency on the acquisition, maintenance, and transfer of trained behaviours were not supported.     

Temporal control in the voicing contrast: Evidence from surgery-related apraxia of speech

ABSTRACT

The goal of this study was to investigate the phonetic realisation of the voicing feature in two tumour resection-related Spanish speakers with apraxia of speech. Temporal parameters related to the phonological contrast of voicing in Spanish have been analysed for intervocalic voiced and voiceless obstruents embedded in isolated words and nonwords, and compared with data collected from healthy speakers. Results indicate that in devoiced productions, where VOT values fitted the ‘voiceless stops’ category, vowel duration values matched those of voiced stops and suggested the preservation of contextual voicing cues. An attempt at preserving a consonant/vowel duration ratio consistent with aerodynamic predictions for voicing contrast has been observed in apraxic correct production as well as in devoicing errors, but not in the control group, which could be interpreted as a compensatory mechanism.     

Segments and syllables in the treatment of apraxia of speech: An investigation of learning and transfer effects

Background: In the treatment of severe apraxia of speech (AOS), single phonemes are often used as training targets. However, until now it remains unclear if segment production can be learned and if patients show transfer effects when a segment trained in isolation is embedded in syllables and words. Speech motor learning in normal language acquisition is based on syllabic rather than segmental learning mechanisms. The syllable is also assumed to be the basic unit of articulatory programming in normal speech.

Aims: In the present study, we investigated the effectiveness of learning single segments as compared to whole syllables in patients with AOS. Besides immediate learning effects, we were particularly interested in transfer effects on trained targets embedded into larger untrained units and in maintenance effects.

Methods & Procedures: Four patients with severe AOS participated in this study. Target segments and target syllables were trained in two separate phases. To examine learning effects, we presented trained and untrained items in isolation immediately before and after a learning phase. Transfer effects of the segmental learning were examined by presenting syllables which contained the target and control phonemes. The transfer of syllabic learning was assessed on the basis of two-syllabic words containing the target and control syllables.

Main Contributions: In the segmental condition, only one patient showed a significant learning effect. Transfer effects onto untrained syllables containing the trained consonants were missing in all patients. After the syllabic training, three patients produced significantly lower error rates on the trained, but not on the control syllables. In two of them, the improvements were still maintained when the syllables were embedded in two-syllabic words.

Conclusions: The lack of segmental learning effects in three patients may be due to the fact that single consonants are artificial speech units we normally do not produce in isolation. The complete absence of transfer effects suggests that intrasyllabic coarticulation is part of the phonetic plan and cannot be mastered by speech apraxic patients without extra exercise. The observed learning effects after the syllabic learning confirm that syllables constitute more natural speech motor units which are easier to re-acquire than single consonants. Furthermore, the embedding of learned monosyllables into unlearned two-syllabic words requires less extra speech motor planning than the embedding of a trained segment into the coarticulated context of a syllable.     

Electrical stimulation over the left inferior frontal gyrus (IFG) determines long-term effects in the recovery of speech apraxia in three chronic aphasics

A number of studies have shown that modulating cortical activity by means of transcranial direct current stimulation (tDCS) affects the performance of both healthy and brain-damaged subjects. In this study, we investigated the potential of tDCS for the recovery of apraxia of speech in 3 patients with stroke-induced aphasia. Over 2 weeks, three aphasic subjects participated in a randomized double-blinded experiment involving intensive language training for their articulatory difficulties in two tDCS conditions. Each subject participated in five consecutive daily sessions of anodic tDCS (20 min, 1 mA) and sham stimulation over the left inferior frontal gyrus (referred to as Broca's area) while they performed a repetition task. By the end of each week, a significant improvement was found in both conditions. However, all three subjects showed greater response accuracy in the anodic than in the sham condition. Moreover, results for transfer of treatment effects, although different across subjects, indicate a generalization of the recovery at the language test. Subjects 2 and 3 showed a significant improvement in oral production tasks, such as word repetition and reading, while Subjects 1 and 2 had an unexpected significant recovery in written naming and word writing under dictation tasks. At three follow-ups (1 week, 1 and 2 months after the end of treatment), response accuracy was still significantly better in the anodic than in sham condition, suggesting a long-term effect on the recovery of their articulatory gestures.