Purpose: We explored the reliability and validity of 2 quantitative approaches to document presence and severity of speech properties associated with apraxia of speech (AOS). Method: A motor speech evaluation was administered to 39 individuals with aphasia. Audio-recordings of the evaluation were presented to 3 experienced clinicians to determine AOS diagnosis and to rate severity of 11 speech dimensions. Additionally, research assistants coded 11 operationalized metrics of articulation, fluency, and prosody in the same speech samples and in recordings from 20 neurologically healthy participants. Results: Agreement among the 3 clinicians was limited for both AOS diagnosis and perceptual scaling, but inter-observer reliability for the operationalized metrics was strong. The relationships between most operationalized metrics and mean severity ratings for corresponding perceptual dimensions were moderately strong and statistically significant. Both perceptual scaling and operationalized quantification approaches were sensitive to the presence or absence of AOS. Conclusions: Perceptual scaling and operationalized metrics are promising quantification techniques that can help establish diagnostic transparency for AOS. However, because satisfactory reliability cannot be assumed for scaling techniques, effective training and calibration procedures should be implemented. Operationalized metrics show strong potential for enhancing diagnostic objectivity and sensitivity.

Variability in the speech production patterns of children with developmental apraxia of speech (DAS) was investigated in a three‐year longitudinal study of three children with DAS. A metric was developed to measure token‐to‐token variability in repeated word productions from connected speech samples. Results suggest that high levels of total token and error token variability and low levels of word target stability and token accuracy characterize the disorder. Overall levels of variability and patterns of change over time differed between participants. Longitudinal patterns were indicative of decreasing total token variability and increasing token accuracy. However, change was not consistently unidirectional for two of the three children in the study, suggesting day‐to‐day performance differences in addition to within‐session variability.

Purpose: To examine the effects and generalization of a modified script training intervention, delivered partly via videoconferencing, on dialogue scripts that were produced by 2 individuals with aphasia. Method: Each participant was trained on 2 personally relevant scripts. Intervention sessions occurred 3 times per week, with a combination of in-person meetings and videoconferencing, and lasted for 3 weeks per script. This study followed a multiple baseline design across scripts. Measures of accuracy, grammatical productivity, speaking rate, and articulatory fluency were obtained during baseline, intervention, and maintenance phases. Generalization probes were administered by challenging participants to engage in a conversation about their script topic with conversation partners who did not follow the script. Results: Both participants showed improvement on all dependent variables for both scripts during and after the intervention phase. Generalization samples showed improved grammatical morpheme use and increased rate of speech over prebaseline samples. Conclusion: There is evidence that script training intervention can improve accuracy, grammatical productivity, speaking rate, and articulatory fluency in script production tasks as well as in more functional conversational tasks. Videoconferencing is a viable method of conducting script training intervention when it is supported by face-to-face intervention sessions, slight modifications to the procedure, and an emphasis on self-cuing skills.

Purpose This study was conducted to evaluate the clinical utility of error variability for differentiating between apraxia of speech (AOS) and aphasia with phonemic paraphasia. Method Participants were 32 individuals with aphasia after left cerebral injury. Diagnostic groups were formed on the basis of operationalized measures of recognized articulatory and prosodic characteristics of AOS and phonemic paraphasia. Sequential repetitions of multisyllabic words were elicited as part of a motor speech evaluation and transcribed phonetically. Four metrics of variability at the syllable and word levels were derived from these transcripts. Results The measures yielded different magnitudes of variability. There were no group differences between participants who displayed speech profiles consistent with AOS and participants who displayed speech profiles indicative of aphasia with phonemic paraphasia. Rather, correlation coefficients and analyses of covariance showed that the variability metrics were significantly mediated by overall error rate. Additionally, variability scores for individuals with salient diagnoses of AOS and conduction aphasia were inconsistent with current diagnostic guidelines. Conclusions The results do not support diagnostic validity of error variability for differentiating between AOS and aphasia with phonemic paraphasia. Future research using error variability metrics should account for overall error rate in the analysis and matching of participant groups.

Vowel inventories and error patterns for three children with suspected developmental apraxia of speech (DAS) were analysed over a 3-year period using phonetic transcriptions of connected speech samples. The children demonstrated complete English vowel inventories except for rhotics. However, accuracy of vowel targets in connected speech did not normalize during this period. No consistent patterns of vowel errors were found. There was no decrease in vowel accuracy with increased utterance length or syllable complexity. Findings indicate persistence of vowel inaccuracy in the presence of a relatively complete vowel inventory. This longitudinal data can help to build consensus on use of vowels as a potential clinical marker for differential diagnosis of DAS.

Purpose: To explore the use of noninvasive functional imaging and “virtual” lesion techniques to study the neural mechanisms underlying motor speech disorders in Parkinson’s disease. Here, we report the use of positron emission tomography (PET) and transcranial magnetic stimulation (TMS) to explain exacerbated speech impairment following subthalamic nucleus deep brain stimulation (STN-DBS) in a patient with Parkinson’s disease. Method: Perceptual and acoustic speech measures, as well as cerebral blood flow during speech as measured by PET, were obtained with STN-DBS on and off. TMS was applied to a region in the speech motor network found to be abnormally active during DBS. Speech disruption by TMS was compared both perceptually and acoustically with speech produced with DBS on. Results: Speech production was perceptually inferior and acoustically less contrastive during left STN stimulation compared to no stimulation. Increased neural activity in left dorsal premotor cortex (PMd) was observed during DBS on. “Virtual” lesioning of this region resulted in speech characterized by decreased speech segment duration, increased pause duration, and decreased intelligibility. Conclusions: This case report provides evidence that impaired speech production accompanying STN-DBS may result from unintended activation of PMd. Clinical application of functional imaging and TMS may lead to optimizing the delivery of STN-DBS to improve outcomes for speech production as well as general motor abilities.