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The use of metal and semimetal van der Waals contacts for 2D semiconducting devices has led to remarkable device optimizations. In comparison with conventional thin-film metal deposition, a reduction in Fermi level pinning at the contact interface for van der Waals contacts results in, generally, lower contact resistances and higher mobilities. Van der Waals contacts also lead to Schottky barriers that follow the Schottky-Mott rule, allowing barrier estimates on material properties alone. In this study, we present a double Schottky barrier model and apply it to a barrier tunable all van der Waals transistor. In a molybdenum disulfide (MoS 2 ) transistor with graphene and few-layer graphene contacts, we find that the model can be applied to extract Schottky barrier heights that agree with the Schottky-Mott rule from simple two-terminal current-voltage measurements at room temperature. Furthermore, we show tunability of the Schottky barrier in-situ using a regional contact gate. Our results highlight the utility of a basic back-to-back diode model in extracting device characteristics in all van der Waals transistors., (Creative Commons Attribution license.)

Purpose: Slow speech rate and abnormal temporal prosody are primary diagnostic criteria for differentiating between people with aphasia who do and do not have apraxia of speech. We sought to identify appropriate cutoff values for abnormal word syllable duration (WSD) in a word repetition task, interpret them relative to a data set of people with chronic aphasia, and evaluate the extent to which manually derived measures could be approximated through an automated process that relied on commercial speech recognition technology., Method: Fifty neurotypical participants produced 49 multisyllabic words during a repetition task. Audio recordings were submitted to an automated speech recognition (ASR) service (IBM Watson) to measure word duration and generate an orthographic transcription. The transcribed words were compared to a lexical database, and the number of syllables was identified. Automatic and manual measures were compared for 50% of the sample. Results were interpreted relative to WSD scores from an existing data set of 195 people with mostly chronic aphasia., Results: ASR correctly identified 83% of target words and 98% of target syllable counts. Automated word duration calculations were longer than manual measures due to imprecise cursor placement. Upon applying regression coefficients to the automated measures and examining the frequency distributions for both manual and estimated measures, a WSD of 303-316 ms was found to indicate longer-than-normal performance (corresponding to the 95th percentile). With this cutoff, 40%-45% of participants with aphasia in our comparison sample had an abnormally long WSD., Conclusions: We recommend using a rounded WSD cutoff score between 303 and 316 ms for manual measures. Future research will focus on customizing automated WSD methods to speech samples from people with aphasia, identifying target words that maximize production and measurement reliability, and developing WSD standard scores based on a large participant sample with and without aphasia.

Background: Care partners of people with aphasia after stroke need various informational supports, such as aphasia education and resources for psychosocial support. However, informational support may vary across clinicians, and access to these supports remains a persistent unmet need. Using implementation science frameworks can help to assess the gap between what is known about an issue and what is occurring in practice., Aim: The aim was to identify barriers to providing informational support for care partners of people with aphasia after stroke., Method and Procedure: We performed a secondary analysis of qualitative data collected from two of our previous studies. New themes were identified by comparing feedback from both speech-language pathologists and care partners, and previously assigned codes were interpreted relative to the Knowledge to Action (KTA) framework., Outcomes and Results: We identified four implementation themes that were specifically related to the action cycle of the KTA framework: (a) Aphasia rehabilitation tends to exclude care partners, (b) aphasia rehabilitation can be hard to understand, (c) structure is lacking for care partner check-ins, and (d) care partner informational support rarely extends beyond the acute phases of recovery., Conclusion: The results suggest that changes are needed at both systemic and care provider levels to ensure that tailored information is provided to care partners of people with aphasia.

Purpose: 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)., Method: 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., Results: 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., Conclusions: 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., Supplemental Material: https://doi.org/10.23641/asha.21807609.

Early detection of cognitive decline is essential to study mild cognitive impairment and Alzheimer's Disease in order to develop targeted interventions and prevent or stop the progression of dementia. This requires continuous and longitudinal assessment and tracking of the related physiological and behavioral changes during daily life. In this paper, we present a low cost and low power wearable system custom designed to track the trends in speech, gait, and cognitive stress while also considering the important human factor needs such as privacy and compliance. In the form factors of a wristband and waist-patch, this multimodal, multi-sensor system measures inertial signals, sound, heart rate, electrodermal activity and pulse transit time. A total power consumption of 2.6 mW without any duty cycling allows for more than 3 weeks of run time between charges when 1500 mAh batteries are used.Clinical Relevance- Much earlier detection of Alzheimer's disease and related dementias may be possible by continuous monitoring of physiological and behavioral state using application specific wearable sensors during the activities of daily life.

Purpose: Although the importance of motivation to successful rehabilitation is frequently acknowledged in the aphasia literature, little evidence-based guidance has been provided on how to support it. The purpose of this tutorial is to introduce a well-validated theory of motivation, self-determination theory (SDT); explain its role as the foundation for the FOURC model of collaborative goal setting and treatment planning; and explain how it may be applied during rehabilitation to support the motivation of people with aphasia., Method: We provide an overview of SDT, explore the link between motivation and psychological wellness, and discuss how psychological needs are addressed in SDT and the FOURC model. Concrete examples from aphasia therapy are used to illustrate main concepts., Conclusions: SDT offers tangible guidance for supporting motivation and wellness. SDT-based practices support positive forms of motivation, which is one of the targets of FOURC. An understanding of SDT's theoretical foundation will help clinicians maximize the impact of collaborative goal setting and aphasia therapy more generally.

Purpose: During motor speech examinations for suspected apraxia of speech (AOS), clients are routinely asked to repeat words several times sequentially. The purpose of this study was to understand the task in terms of the relationship among consecutive attempts. We asked to what extent phonemic accuracy changes across trials and whether the change is predicted by AOS diagnosis and sound production severity., Method: One hundred thirty-three participants were assigned to four diagnostic groups based on quantitative metrics (aphasia plus AOS, aphasia-only, and aphasia with two borderline speech profiles). Each participant produced four multisyllabic words 5 times consecutively. These productions were audio-recorded and transcribed phonetically and then summarized as the proportion of target phonemes that was produced accurately. Nonparametric statistics were used to analyze percent change in accuracy from the first to the last production based on diagnostic group and a broad measure of speech sound accuracy., Results: Accuracy on the repeated words deteriorated across trials for all groups, showing reduced accuracy from the first to the last repetition for 62% of participants. Although diagnostic groups differed on the broad measure of speech sound accuracy, severity classification based on this measure did not determine degree of deterioration on the repeated words task., Discussion: Responding to a request to say multisyllabic words 5 times sequentially is challenging for people with aphasia with and without AOS, and as such, performance is prone to errors even with mild impairment. For most, the task does not encourage self-correction. Instead, it promotes errors, regardless of diagnosis, and is, therefore, useful for screening purposes.

Hepatic encephalopathy (HE) is a complication of cirrhosis that benefits from early diagnosis and treatment. We aimed to characterize speech patterns of individuals with HE to investigate its potential to diagnose and monitor HE. This was a single-center prospective cohort study that included participants with cirrhosis with HE (minimal HE [MHE] and overt HE [OHE]), cirrhosis without HE, and participants without liver disease. Audio recordings of reading, sentence repetition, and picture description tasks were obtained from these groups. Two certified speech-language pathologists assessed speech rate (words per minute) and articulatory precision. An overall severity metric was derived from these measures. Cross-sectional analyses were performed using nonparametric Wilcoxon statistics to evaluate group differences. Change over time in speech measures was analyzed descriptively for individuals with HE. The study included 43 total participants. Speech results differed by task, but the overall pattern showed slower speech rate and less precise articulation in participants with OHE compared to other groups. When speech rate and precision ratings were combined into a single speech severity metric, the impairment of participants with OHE was more severe than all other groups, and MHE had greater speech impairment than non-liver disease controls. As OHE improved clinically, participants showed notable improvement in speech rate. Participants with OHE demonstrated impaired speech rate, precision, and speech severity compared with non-liver disease and non-HE cirrhosis. Participants with MHE had less pronounced impairments. Speech parameters improved as HE clinically improved. Conclusion: These data identify speech patterns that could improve HE diagnosis, grading, and remote monitoring., (© 2022 The Authors. Hepatology Communications published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Purpose Of the three currently recognized variants of primary progressive aphasia, behavioral differentiation between the nonfluent/agrammatic (nfvPPA) and logopenic (lvPPA) variants is particularly difficult. The challenge includes uncertainty regarding diagnosis of apraxia of speech, which is subsumed within criteria for variant classification. The purpose of this study was to determine the extent to which a variety of speech articulation and prosody metrics for apraxia of speech differentiate between nfvPPA and lvPPA across diverse speech samples. Method The study involved 25 participants with progressive aphasia (10 with nfvPPA, 10 with lvPPA, and five with the semantic variant). Speech samples included a word repetition task, a picture description task, and a story narrative task. We completed acoustic analyses of temporal prosody and quantitative perceptual analyses based on narrow phonetic transcription and then evaluated the degree of differentiation between nfvPPA and lvPPA participants (with the semantic variant serving as a reference point for minimal speech production impairment). Results Most, but not all, articulatory and prosodic metrics differentiated statistically between the nfvPPA and lvPPA groups. Measures of distortion frequency, syllable duration, syllable scanning, and-to a limited extent-syllable stress and phonemic accuracy showed greater impairment in the nfvPPA group. Contrary to expectations, classification was most accurate in connected speech samples. A customized connected speech metric-the narrative syllable duration-yielded excellent to perfect classification accuracy. Discussion Measures of average syllable duration in multisyllabic utterances are useful diagnostic tools for differentiating between nfvPPA and lvPPA, particularly when based on connected speech samples. As such, they are suitable candidates for automatization, large-scale study, and application to clinical practice. The observation that both speech rate and distortion frequency differentiated more effectively in connected speech than on a motor speech examination suggests that it will be important to evaluate interactions between speech and discourse production in future research.

Machine learning methods are changing the way data is analyzed. One of the most powerful and widespread applications of these techniques is in image segmentation wherein disparate objects of a digital image are partitioned and classified. Here we present an image segmentation program incorporating a series of unsupervised clustering algorithms for the automatic thickness identification of two-dimensional materials from digital optical microscopy images. The program identifies mono- and few-layer flakes of a variety of materials on both opaque and transparent substrates with a pixel accuracy of roughly 95%. Contrasting with previous attempts, application generality is achieved through preservation and analysis of all three digital color channels and Gaussian mixture model fits to arbitrarily shaped data clusters. Our results provide a facile implementation of data clustering for the universal, automatic identification of two-dimensional materials exfoliated onto any substrate.

Recently, a multilevel analytic approach called Main Concept, Sequencing, and Story Grammar (MSSG) was presented along with preliminary normative information. MSSG analyses leverage the strong psychometrics and rich procedural knowledge of both main concept analysis and story grammar component coding, complementing it with easy-to-obtain sequencing information for a rich understanding of discourse informativeness and macrostructure. This study is the next critical step for demonstrating the clinical usefulness of MSSG's six variables (main concept composite, sequencing, main concept+sequencing, essential story grammar components, total episodic components, and episodic complexity) for persons with aphasia (PWAs). We present descriptive statistical information for MSSG variables for a large sample of PWAs and compare their performance to a large sample of persons not brain injured (PNBIs). We observed significant differences between PWAs and PNBIs for all MSSG variables. These differences occurred at the omnibus group level and for each aphasia subtype, even for PWAs with very mild impairment that is not detected with standardized aphasia assessment. Differences between PWAs and PNBIs were also practically significant, with medium to large effect sizes observed for nearly all aphasia subtypes and MSSG variables. This work deepens our understanding of discourse informativeness and macrostructure in PWAs and further develops an efficient tool for research and clinical use. Future research should investigate ways to expand MSSG analyses and to improve sensitivity and specificity.

Purpose: There is persistent uncertainty about whether sound error consistency is a valid criterion for differentiating between apraxia of speech (AOS) and aphasia with phonemic paraphasia. The purpose of this study was to determine whether speakers with a profile of aphasia and AOS differ in error consistency from speakers with aphasia who do not have AOS. By accounting for differences in overall severity and using a sample size well over three times that of the largest study on the topic to date, our ambition was to resolve the existing controversy., Method: We analyzed speech samples from 171 speakers with aphasia and completed error consistency analysis for 137 of them. The experimental task was to repeat four multisyllabic words five times successively. Phonetic transcriptions were coded for four consistency indices (two at the sound-level and two at the word-level). We then used quantitative metrics to assign participants to four diagnostic groups (one aphasia plus AOS group, one aphasia only group, and two groups with intermediate speech profiles). Potential consistency differences were examined with ANCOVA, with error frequency as a continuous covariate., Results: Error frequency was a strong predictor for three of the four consistency metrics. The magnitude of consistency for participants with AOS was either similar or lower compared to that of participants with aphasia only. Despite excellent transcription reliability and moderate to excellent coding reliability, three of the four consistency indices showed limited measurement reliability., Discussion: People with AOS and people with aphasia often produce inconsistent variants of errors when they are asked to repeat challenging words several times sequentially. The finding that error consistency is similar or lower in aphasia with AOS than in aphasia without AOS is incompatible with recommendations that high error consistency be used as a diagnostic criterion for AOS. At the same time, group differences in the opposite direction are not sufficiently systematic to warrant use for differential diagnosis between aphasia with AOS and aphasia with phonemic paraphasia. Greater attention should be given to error propagation when estimating reliability of derived measurements.

Purpose The purpose of this study was to compare the utility of two automated indices of lexical diversity, the Moving-Average Type-Token Ratio (MATTR) and the Word Information Measure (WIM), in predicting aphasia diagnosis and responding to differences in severity and aphasia subtype. Method Transcripts of a single discourse task were analyzed for 478 speakers, 225 of whom had aphasia per an aphasia battery. We calculated the MATTR and the WIM for each participant. We compared the group means among speakers with aphasia, neurotypical controls, and left-hemisphere stroke survivors with mild aphasia not detected by an aphasia battery. We examined whether each measure distinguished levels of aphasia severity and subtypes of aphasia. We used each measure to classify aphasia versus neurotypical control and compared the areas under the curve. Results The WIM and the MATTR differentiated among people with aphasia, neurotypical controls, and people with mild aphasia. Both measures demonstrated moderately high predictive accuracy in classifying aphasia. The WIM demonstrated greater sensitivity to aphasia severity and subtype compared to the MATTR. Conclusions The WIM and the MATTR are promising measures that quantify lexical diversity in different and complementary ways. The WIM may be more useful for quantifying the effect of treatment or disease progression, whereas the MATTR may be more useful for discriminating discourse produced by people with very mild aphasia from discourse produced by neurotypical controls. Further validation is required.

Purpose In comparison to the large literature on moderate to severe aphasia, very little is known about aphasia of the mildest severity and whether intervention may be warranted. The purpose of this pilot study was to characterize challenges experienced by people who have recovered to the point that they score normally on aphasia batteries yet report they continue to have aphasia. Method Five people with aphasia who scored above the Western Aphasia Battery-Aphasia Quotient (Kertesz, 2007) cutoff for aphasia participated in a semistructured interview. A descriptive qualitative design was used to analyze subjective descriptions of difficulties in everyday communication situations within a framework for living with aphasia. Results Participants reported salient communication difficulties, reduced social participation, difficulties returning to work, a continual need to concentrate when engaging in language tasks, and a keen awareness of persisting impairments. Conclusion People with very mild aphasia experience salient language difficulties, and these difficulties have an adverse effect on multiple domains of living successfully with aphasia. Further investigation toward better methods of assessment and intervention is warranted.

Purpose Because people with aphasia (PWA) frequently interact with partners who are unresponsive to their communicative attempts, we investigated how partner responsiveness affects quantitative measures of spoken language and subjective reactions during story retell. Method A quantitative study and a qualitative study were conducted. In Study 1, participants with aphasia and controls retold short stories to a communication partner who indicated interest through supportive backchannel responses (responsive) and another who indicated disinterest through unsupportive backchannel responses (unresponsive). Story retell accuracy, delivery speed, and ratings of psychological stress were measured and compared. In Study 2, participants completed semistructured interviews about their story retell experience, which were recorded, transcribed, and coded using qualitative analysis software. Results Quantitative results revealed increased psychological stress and decreased delivery speed across all participant groups during the unresponsive partner condition. Effects on delivery speed were more consistent for controls than participants with aphasia. Qualitative results revealed that participants with aphasia were more attuned to unresponsive partner behaviors than controls and reported stronger and more frequent emotional reactions. Partner responsiveness also affected how PWA perceived and coped with the communication experience. Conclusions Combined quantitative and qualitative findings suggest that, while unresponsive communication partners may not have robust effects on spoken language, they elicit strong emotional reactions from PWA and affect their communication experience. These findings support the need for communication partner training and suggest that training PWA on emotion regulation or relaxation techniques may help assuage their anxiety during socially challenging everyday communication and increase social participation. Supplemental Material https://doi.org/10.23641/asha.11368028.

Purpose Slowed speech and interruptions to the flow of connected speech are common in aphasia. These features are also observed during dual-task performance for neurotypical adults. The purposes of this study were to determine (a) whether indices of fluency related to cognitive-linguistic versus motor processing would differ between speakers with aphasia plus apraxia of speech (AOS) and speakers with aphasia only and (b) whether cognitive load reduces fluency in speakers with aphasia with and without AOS. Method Fourteen speakers with aphasia (7 with AOS) and 7 neurotypical controls retold short stories alone (single task) and while simultaneously distinguishing between a high and a low tone (dual task). Their narrative samples were analyzed for speech fluency according to sample duration, speech rate, pause/fill time, and repetitions per syllable. Results As expected, both speaker groups with aphasia spoke slower and with more pauses than the neurotypical controls. The speakers with AOS produced more repetitions and longer samples than controls, but they did not differ on these measures from the speakers with aphasia without AOS. Relative to the single-task condition, the dual-task condition increased the duration of pauses and fillers for all groups but reduced speaking rate only for the control group. Sample duration and frequency of repetitions did not change in response to cognitive load. Conclusions Speech output in aphasia becomes less fluent when speakers have to engage in simultaneous tasks, as is typical in everyday conversation. Although AOS may lead to more sound and syllable repetitions than normal, speaking tasks other than narrative discourse might better capture this specific type of disfluency. Future research is needed to confirm and expand these preliminary findings. Supplemental Material https://doi.org/10.23641/asha.8847845.

Background: Up to 40% of stroke survivors acquire aphasia and require long-term caregiver assistance after discharge from the hospital. Caregivers assume multiple roles as they help people with aphasia to access outpatient rehabilitative care in an increasingly person-centred model of care. Examining caregiver roles and how different stakeholders in the rehabilitative journey perceive these roles may be the first step in providing more tailored support to caregivers and improving outcomes for both caregivers and people with aphasia., Aims: To characterize the roles caregivers assume while navigating outpatient rehabilitative care for people with aphasia after stroke from the perspective of different stakeholders in the rehabilitative process., Methods & Procedures: Thirty-six people participated in the study, including seven caregivers, 22 stroke survivors with aphasia and seven healthcare providers. Focus groups were conducted, and an iterative thematic analysis was used to identify themes., Outcomes & Results: Results indicate that caregivers are perceived differently by varying stakeholders, and that caregivers adopt diverse roles as advocates, therapists, motivators and guardians. They assume these roles in order to fill gaps in services or otherwise to facilitate the recovery journey for the person with aphasia., Conclusions & Implications: This study provides a valuable glimpse into how varying stakeholders view the role of the caregiver during rehabilitation for people with aphasia after stroke. Providing caregivers with the training and support they need throughout the recovery journey by treating them as partners in the process may mitigate the perception of caregivers as feeling compelled to adopt multiple roles., (© 2019 Royal College of Speech and Language Therapists.)

Purpose Many communication disorders result in speech sound errors that listeners perceive as phonemic errors. Unfortunately, manual methods for calculating phonemic error frequency are prohibitively time consuming to use in large-scale research and busy clinical settings. The purpose of this study was to validate an automated analysis based on a string metric-the unweighted Levenshtein edit distance-to express phonemic error frequency after left hemisphere stroke. Method Audio-recorded speech samples from 65 speakers who repeated single words after a clinician were transcribed phonetically. By comparing these transcriptions to the target, we calculated the percent segments with a combination of phonemic substitutions, additions, and omissions and derived the phonemic edit distance ratio, which theoretically corresponds to percent segments with these phonemic errors. Results Convergent validity between the manually calculated error frequency and the automated edit distance ratio was excellent, as demonstrated by nearly perfect correlations and negligible mean differences. The results were replicated across 2 speech samples and 2 computation applications. Conclusions The phonemic edit distance ratio is well suited to estimate phonemic error rate and proves itself for immediate application to research and clinical practice. It can be calculated from any paired strings of transcription symbols and requires no additional steps, algorithms, or judgment concerning alignment between target and production. We recommend it as a valid, simple, and efficient substitute for manual calculation of error frequency.

Purpose The aims of the study were to determine dual-task effects on content accuracy, delivery speed, and perceived effort during narrative discourse in people with moderate, mild, or no aphasia and to explore subjective reactions to retelling a story with a concurrent task. Method Two studies (1 quantitative and 1 qualitative) were conducted. In Study 1, participants with mild or moderate aphasia and neurotypical controls retold short stories in isolation and while simultaneously distinguishing between high and low tones. Story retell accuracy (speech productivity and efficiency), speed (speech rate, repetitions, and pauses), and perceived effort were measured and compared. In Study 2, participants completed semistructured interviews about their story retell experience. These interviews were recorded, transcribed orthographically, and coded qualitatively using thematic analysis. Results The dual task interfered more with spoken language of people with aphasia than controls, but different speed-accuracy trade-off patterns were noted. Participants in the moderate aphasia group reduced accuracy with little alteration to speed, whereas participants in the mild aphasia group maintained accuracy and reduced their speed. Participants in both groups also reported more negative emotional and behavioral reactions to the dual-task condition than their neurotypical peers. Intentional strategies for coping with the cognitive demands of the dual-task condition were only reported by participants with mild aphasia. Conclusion The findings suggest that, although communicating with a competing task is more difficult for people with aphasia than neurotypical controls, participants with mild aphasia may be better able to cope with cognitively demanding communication situations than participants with moderate aphasia. Supplemental Material https://doi.org/10.23641/asha.8233391.

Purpose Collaborative goal setting is at the heart of person-centered rehabilitation but can be challenging, particularly in the area of aphasia. The purpose of this clinical focus article is to present a step-by-step model for forming a collaborative partnership with clients to develop an intervention plan that follows the client's lead, addresses communicative participation, and integrates multiple treatment strategies. Method We introduce the rationale and core features of a 4-step and 4-pronged process (the FOURC model) and illustrate its application through 3 cases of people with aphasia who were treated in outpatient rehabilitation. Conclusions The model invites client initiative in a clinically feasible manner while supporting the clinician's role in guiding the intervention based on professional expertise and growing familiarity with the case. Outcomes observed in case studies include strengthened motivation and improved real-life communication.

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.

Impaired production of prosody is considered a primary diagnostic criterion for apraxia of speech. In this study, we examined diagnostic relevance for five word-level prosody measures. Seven speakers with AOS, nine with aphasia and no AOS, and 19 age-matched neurotypical controls produced nine words consisting of three or four syllables. Lexical stress indices were computed based on relative values for duration, fundamental frequency, and intensity across pairs of unstressed-stressed syllables with varying intrinsic vowel duration contrast patterns. A simple average syllable duration measure was also obtained. AOS speakers differed from the other two groups on three metrics that were solely or primarily derived from duration measures. The degree of diagnostic overlap was smallest for the syllable duration metric, which also showed the strongest inter-observer reliability and most complete overlap between neurotypical speakers and speakers with aphasia and no AOS. Vowel intrinsic durational properties affected lexical stress metrics significantly, indicating a need to select word targets purposefully. Based on these results, it appears that the average syllable duration metric is a more stable and informative alternative for differential diagnostic purposes. The results will, however, need to be replicated in a larger sample.

Objective: Speech sound errors are common in people with a variety of communication disorders and can result in impaired message transmission to listeners. Valid and reliable metrics exist to quantify this problem, but they are rarely used in clinical settings due to the time-intensive nature of speech transcription by humans. Automated speech recognition (ASR) technologies have advanced substantially in recent years, enabling them to serve as realistic proxies for human listeners. This study aimed to determine how closely transcription scores from human listeners correspond to scores from an ASR system., Patients and Methods: Sentence recordings from 10 stroke survivors with aphasia and apraxia of speech were transcribed orthographically by 3 listeners and a web-based ASR service. Adjusted transcription scores were calculated for all samples based on accuracy of transcribed content words., Results: As expected, transcription scores were significantly higher for the humans than for ASR. However, intraclass correlations revealed excellent agreement among the humans and ASR systems, and the systematically lower scores for computer speech recognition were effectively equalized simply by adding the regression intercept., Conclusions: The results suggest the clinical feasibility of supplementing or substituting human transcriptions with computer-generated scores, though extension to other speech disorders requires further research., (© 2019 S. Karger AG, Basel.)

Purpose: 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., Method: 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., Results: 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., Conclusions: 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.

Purpose: We sought to characterize articulatory distortions in apraxia of speech and aphasia with phonemic paraphasia and to evaluate the diagnostic validity of error frequency of distortion and distorted substitution in differentiating between these disorders., Method: Study participants were 66 people with speech sound production difficulties after left-hemisphere stroke or trauma. They were divided into 2 groups on the basis of word syllable duration, which served as an external criterion for speaking rate in multisyllabic words and an index of likely speech diagnosis. Narrow phonetic transcriptions were completed for audio-recorded clinical motor speech evaluations, using 29 diacritic marks., Results: Partial voicing and altered vowel tongue placement were common in both groups, and changes in consonant manner and place were also observed. The group with longer word syllable duration produced significantly more distortion and distorted-substitution errors than did the group with shorter word syllable duration, but variations were distributed on a performance continuum that overlapped substantially between groups., Conclusions: Segment distortions in focal left-hemisphere lesions can be captured with a customized set of diacritic marks. Frequencies of distortions and distorted substitutions are valid diagnostic criteria for apraxia of speech, but further development of quantitative criteria and dynamic performance profiles is necessary for clinical utility.

Purpose: This study was intended to document speech recovery for 1 person with acquired apraxia of speech quantitatively and on the basis of her lived experience., Method: The second author sustained a traumatic brain injury that resulted in acquired apraxia of speech. Over a 2-year period, she documented her recovery through 22 video-recorded monologues. We analyzed these monologues using a combination of auditory perceptual, acoustic, and qualitative methods., Results: Recovery was evident for all quantitative variables examined. For speech sound production, the recovery was most prominent during the first 3 months, but slower improvement was evident for many months. Measures of speaking rate, fluency, and prosody changed more gradually throughout the entire period. A qualitative analysis of topics addressed in the monologues was consistent with the quantitative speech recovery and indicated a subjective dynamic relationship between accuracy and rate, an observation that several factors made speech sound production variable, and a persisting need for cognitive effort while speaking., Conclusions: Speech features improved over an extended time, but the recovery trajectories differed, indicating dynamic reorganization of the underlying speech production system. The relationship among speech dimensions should be examined in other cases and in population samples. The combination of quantitative and qualitative analysis methods offers advantages for understanding clinically relevant aspects of recovery.

Background: People with aphasia (PWA) are frequently perceived less favorably by listeners than their peers. These perceptions include incorrect assumptions that can prevent successful social interactions. While communication partner training has been shown to improve social outcomes related to the listener (see e.g., Kagan, Black, Duchan, Simmons-Mackie, & Square, 2001), changing the verbal output of PWA may also yield more favorable listener perceptions about the speech, speaker, and their own affective response. We investigated the effects of artificially altered fluency (i.e., simulated fluency) on listeners' subjective impressions., Aims: The purpose of the study was to (1) confirm that listeners perceive PWA less favorably than their neurologically healthy peers and (2) determine the effects of simulated fluency on listener perceptions about PWA., Method & Procedures: Thirty-eight listeners heard nine narrative monologue language samples from three conditions (i.e., speakers with nonfluent aphasia, simulated fluent samples from the same speakers, and neurologically healthy speakers). Listeners responded to a nine-item questionnaire that probed perceptions about speech output, speaker attributes, and listener feelings., Outcomes & Results: Listeners perceived PWA less favorably than their neurologically healthy peers. Simulated fluency yielded more positive listener perceptions for all questionnaire items except speech intelligibility, which was unchanged by simulated fluency., Conclusions: Simulated fluency improved listener perceptions of PWA significantly, indicating that speech fluency may be a socially valid treatment target in aphasia. Beyond direct training of communication partners, changing the verbal output of aphasic speech can also yield more positive listener perceptions of PWA.

Purpose: To study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not expected to improve speech fluency., Method: Ten participants with APH/AOS and 10 neurologically healthy (NH) participants were studied under both feedback conditions. To allow examination of individual responses, we used an ABACA design. Effects were examined on syllable rate, disfluency duration, and vocal intensity., Results: Seven of 10 APH/AOS participants increased fluency with masking by increasing rate, decreasing disfluency duration, or both. In contrast, none of the NH participants increased speaking rate with MAF. In the AAF condition, only 1 APH/AOS participant increased fluency. Four APH/AOS participants and 8 NH participants slowed their rate with AAF., Conclusions: Speaking with MAF appears to increase fluency in a subset of individuals with APH/AOS, indicating that overreliance on auditory feedback monitoring may contribute to their disorder presentation. The distinction between responders and nonresponders was not linked to AOS diagnosis, so additional work is needed to develop hypotheses for candidacy and underlying control mechanisms.

Background: Considerable attention has been given to the identification of depression in stroke survivors with aphasia, but there is more limited information about other mood states. Visual analog scales are often used to collect subjective information from people with aphasia. However, the validity of these methods for communicating about mood has not been established in people with moderately to severely impaired language., Objective: The dual purposes of this study were to characterize the relative endorsement of negative and positive mood states in people with chronic aphasia after stroke and to examine congruent validity for visual analog rating methods for people with a range of aphasia severity., Methods: Twenty-three left-hemisphere stroke survivors with aphasia were asked to indicate their present mood by using two published visual analog rating methods. The congruence between the methods was estimated through correlation analysis, and scores for different moods were compared., Results: Endorsement was significantly stronger for "happy" than for mood states with negative valence. At the same time, several participants displayed pronounced negative mood compared to previously published norms for neurologically healthy adults. Results from the two rating methods were moderately and positively correlated., Conclusions: Positive mood is prominent in people with aphasia who are in the chronic stage of recovery after stroke, but negative moods can also be salient and individual presentations are diverse. Visual analog rating methods are valid methods for discussing mood with people with aphasia; however, design optimization should be explored.

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.

Background: People with aphasia (PWA) are frequently disregarded as reliable respondents because their language problems may restrict their responses to oral and written questioning. Consequently, family members are often asked to speak on their behalf. The Life Interests and Values (LIV) Cards are a nonlinguistic, picture-based instrument designed for communicating directly with PWA about their current and desired life activities., Purpose: The goals of this study were to (1) explore utility of LIV Cards for interviewing PWA and (2) examine congruence between responses of PWA and proxies., Method: Study participants were 10 PWA with varying language and cognitive abilities and 10 family member proxies. Both groups participated in LIV Card interviews to identify current and preferred activities of the PWA. Core interview times for the PWA and percentage of selected activities for 4 activity categories were calculated, as was item-by-item response congruency between PWA and proxies., Results: All 10 PWA completed LIV Cards interviews in 45 minutes or less. There were individualized response patterns regarding activity participation and preferences. Mean point-to-point agreement between PWA and their proxies was 74% for current activities and 71% for activity preferences of the PWA., Conclusions: PWA were able to provide information about their current and preferred involvement in life activities through use of the LIV Cards. Family members did not predict activity choices and desires of PWA with full accuracy. The LIV Cards appear to be a viable tool for setting goals and discussing life priorities of PWA.

Purpose: The purpose of this study was twofold: (a) to determine maxillary arch dimensions of children with repaired cleft lip and palate (CLP) who produced middorsum palatal stops and (b) to describe some spectral characteristics of middorsum palatal stops., Method: Maxillary arch width, length, and height dimensions and first spectral moments of /t/-/k/ contrast words were determined for three groups of children ages 7-11 years: (a) with CLP who were clinically judged to produce middorsum palatal stops ( n = 5), (b) with CLP but without middorsum palatal stops ( n = 6), and (c) typically developing controls ( n = 8). Validity of clinical judgments of middorsum palatal stops was assessed by adult listeners via forced-choice identification of /t/-/k/ contrast words., Results: Listeners confirmed production of middorsum palatal stops for 4 of 5 children with CLP. These children had (a) the narrowest anterior maxillary arch width relative to posterior arch width ( p = .011) and (b) the lowest first spectral moment for /t/ targets ( p = .001) and the lowest /t/-/k/ difference ( p = .010)., Conclusion: Middorsum palatal stops may occur in children with repaired CLP in response to limited anterior oral cavity space due to restricted (or collapsed) maxillary arches. First spectral moment characteristics of middorsum palatal stops are consistent with backed lingual placement during stop release.

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.

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.

Objective: To determine the reliability and validity of a computer-mediated, 50-word intelligibility test designed to be a global measure of severity of speech disability in children with repaired cleft lip and palate., Design: A prospective between-group design was used with convenience sampling of patients from a university craniofacial center., Participants: A total of 38 children between the ages of 4 and 9 years participated. Of these, 22 had repaired cleft lip and palate; whereas, 16 had no clefts. Twenty adults served as listeners., Main Outcome Measure(s): Speech intelligibility scores were calculated for repeated administrations of a single-word test based upon the number of correct orthographically transcribed words by four groups of five listeners per child. Measures of parallel forms, interlistener, and intralistener reliabilities were estimated; measures of construct validity were also determined., Results: All measures of reliability were adequate. Parallel forms reliability of the test based upon mean scores from five listeners per child was high (r = .97). Thirty-seven of 38 children had differences between forms of 11 percentage points or less. Construct validity of the test was shown by (1) significantly lower speech intelligibility scores for children with cleft lip and palate than controls and (2) a moderately high correlation (r = .79) between intelligibility scores and percent consonants correct for all children., Conclusions: A computerized, single-word intelligibility test was described that appears to be a reliable and valid measure of global speech deficits in children with cleft lip and palate. Additional development of the test may further facilitate standardized assessment of children with cleft lip and palate.

Unlabelled: This study was designed to estimate test-retest reliability of orthographic speech intelligibility testing in speakers with aphasia and AOS and to examine its relationship to the consistency of speaker and listener responses. Monosyllabic single word speech samples were recorded from 13 speakers with coexisting aphasia and AOS. These words were transcribed phonetically by two trained listeners and also presented to non-brain-damaged listeners for identification in a computerized speech intelligibility test. Overall intelligibility scores were computed for each speaker, and word-by-word responses for individual words were examined for both speaker and listener consistency. The clinical feasibility of the approach was supported by a strong correlation between scores from the phonetic transcription and speech intelligibility tests and by strong test-retest reliability for all speakers. Detailed analyses of individual responses indicated that the intelligibility test stability was not due to consistency either in the kind of errors speakers made or in the responses listeners gave when they heard a word different from the target., Learning Outcomes: The reader will be able to describe the purpose of single word speech intelligibility testing in individuals with aphasia and apraxia of speech and to discuss the relationship between word-by-word production consistency and overall test-retest reliability., (Copyright © 2010 Elsevier Inc. All rights reserved.)

BACKGROUND: Previous work indicates that single word intelligibility tests developed for dysarthria are sensitive to segmental production errors in aphasic individuals with and without apraxia of speech. However, potential listener learning effects and difficulties adapting elicitation procedures to coexisting language impairments limit their applicability to left hemisphere stroke survivors. AIMS: The main purpose of this study was to examine basic psychometric properties for a new monosyllabic intelligibility test developed for individuals with aphasia and/or AOS. A related purpose was to examine clinical feasibility and potential to standardize a computer-mediated administration approach. METHODS #ENTITYSTARTX00026; PROCEDURES: A 600-item monosyllabic single word intelligibility test was constructed by assembling sets of phonetically similar words. Custom software was used to select 50 target words from this test in a pseudo-random fashion and to elicit and record production of these words by 23 speakers with aphasia and 20 neurologically healthy participants. To evaluate test-retest reliability, two identical sets of 50-word lists were elicited by requesting repetition after a live speaker model. To examine the effect of a different word set and auditory model, an additional set of 50 different words was elicited with a pre-recorded model. The recorded words were presented to normal-hearing listeners for identification via orthographic and multiple-choice response formats. To examine construct validity, production accuracy for each speaker was estimated via phonetic transcription and rating of overall articulation. OUTCOMES #ENTITYSTARTX00026; RESULTS: Recording and listening tasks were completed in less than six minutes for all speakers and listeners. Aphasic speakers were significantly less intelligible than neurologically healthy speakers and displayed a wide range of intelligibility scores. Test-retest and inter-listener reliability estimates were strong. No significant difference was found in scores based on recordings from a live model versus a pre-recorded model, but some individual speakers favored the live model. Intelligibility test scores correlated highly with segmental accuracy derived from broad phonetic transcription of the same speech sample and a motor speech evaluation. Scores correlated moderately with rated articulation difficulty. CONCLUSIONS: We describe a computerized, single-word intelligibility test that yields clinically feasible, reliable, and valid measures of segmental speech production in adults with aphasia. This tool can be used in clinical research to facilitate appropriate participant selection and to establish matching across comparison groups. For a majority of speakers, elicitation procedures can be standardized by using a pre-recorded auditory model for repetition. This assessment tool has potential utility for both clinical assessment and outcomes research.

This study was designed to examine the feasibility of using the spectral mean and/or spectral skewness to distinguish between alveolar and palato-alveolar fricatives produced by individual adult speakers of English. Five male and five female speaker participants produced 100 CVC words with an initial consonant /s/ or /ʃ/. The spectral mean and skewness were derived every 10 milliseconds throughout the fricative segments and plotted for all productions. Distinctions were examined for each speaker through visual inspection of these time history plots and statistical comparisons were completed for analysis windows centered 50 ms after the onset of the fricative segment. The results showed significant differences between the alveolar and palato-alveolar fricatives for both the mean and skewness values. However, there was considerable inter-speaker overlap, limiting the utility of the measures to evaluate the adequacy of the phonetic distinction. When the focus shifted to individual speakers rather than average group performance, only the spectral mean distinguished consistently between the two phonetic categories. The robustness of the distinction suggests that intra-speaker overlap in spectral mean between prevocalic /s/ and /ʃ/ targets may be indicative of abnormal fricative production and a useful measure for clinical applications.

The contribution of the nasal murmur and vocalic formant transition to the perception of the [m]-[n] distinction by adult listeners was investigated for speakers of different ages in both consonant-vowel (CV) and vowel-consonant (VC) syllables. Three children in each of the speaker groups 3, 5, and 7 years old, and three adult females and three adult males produced CV and VC syllables consisting of either [m] or [n] and followed or preceded by [i ae u a], respectively. Two productions of each syllable were edited into seven murmur and transitions segments. Across speaker groups, a segment including the last 25 ms of the murmur and the first 25 ms of the vowel yielded higher perceptual identification of place of articulation than any other segment edited from the CV syllable. In contrast, the corresponding vowel+murmur segment in the VC syllable position improved nasal identification relative to other segment types for only the adult talkers. Overall, the CV syllable was perceptually more distinctive than the VC syllable, but this distinctiveness interacted with speaker group and stimulus duration. As predicted by previous studies and the current results of perceptual testing, acoustic analyses of adult syllable productions showed systematic differences between labial and alveolar places of articulation, but these differences were only marginally observed in the youngest children's speech. Also predicted by the current perceptual results, these acoustic properties differentiating place of articulation of nasal consonants were reliably different for CV syllables compared to VC syllables. A series of comparisons of perceptual data across speaker groups, segment types, and syllable shape provided strong support, in adult speakers, for the "discontinuity hypothesis" [K. N. Stevens, in Phonetic Linguistics: Essays in Honor of Peter Ladefoged, edited by V. A. Fromkin (Academic, London, 1985), pp. 243-255], according to which spectral discontinuities at acoustic boundaries provide critical cues to the perception of place of articulation. In child speakers, the perceptual support for the "discontinuity hypothesis" was weaker and the results indicative of developmental changes in speech production.

Previous research has established that the duration of stressed word stem vowels is shorter in polysyllabic words than in monosyllabic words for normal speakers and for speakers with aphasia and apraxia of speech (AOS). However, the results are inconsistent across studies with regard to the magnitude and pattern of the duration reduction for apraxic speakers. We hypothesized that this inconsistency may be explained based on different relative measures of duration reduction. A speech sample was obtained from 10 aphasic speakers with AOS, 10 aphasic speakers without AOS, and 10 normal controls. As predicted, the use of two different relative measures resulted in different vowel reduction patterns, both of which were consistent with previous reports. The results further indicate that the production of polysyllabic words is particularly taxing in AOS and is associated with a substantial reduction of speaking rate compared to other aphasic and normal speakers., (Copyright 2001 Elsevier Science.)

Recent research on 5- to 11-year-old children's perception of stop consonants and vowels indicates that they can generally identify these sounds with relatively high accuracy from short duration stimulus onsets [Ohde et al., J. Acoust. Soc. Am. 97, 3800-3812 (1995); Ohde et al., J. Acoust. Soc. Am. 100, 3813-3824 (1996)]. The purpose of the current experiments was to determine if younger children, aged 3-4 years, can also recover consonant and vowel features from stimulus onsets. Ten adults, ten 3-year olds, and ten 4-year-olds listened to synthesized syllables composed of combinations of [b d g] and [i u a]. The synthesis parameters included manipulations of the following stimulus variables: formant transition (moving or straight), noise burst (present or absent), and voicing duration (10, 30, or 46 ms). Developmental effects were found for the perception of both stop consonants and vowels. In general, adults identified these sounds at a significantly higher level than children, and perception by 4-year-olds was significantly better than 3-year-olds. A developmental effect of dynamic formant motion was obtained, but it was limited to only the [g] stop consonant. Stimulus duration affected the children's perception of vowels indicating that they may utilize additional auditory information to a much greater extent than adults. The results support the importance of information in stimulus onsets for syllable identification, and developmental changes in sensitivity to these cues for consonant and vowel perception.

The purpose of this study was to assess the perceptual role of brief synthetic consonant-vowel syllables as cues for vowel perception in children and adults. Nine types of consonant-vowel syllables comprised of the stops [b d g] followed by the vowels [i a u] were synthesized. Stimuli were generated with durations of 10, 30, or 46 ms, and with or without formant transition motion. Eight children at each of five age levels (5, 6, 7, 9, and 11 years) and a control group of eight adults were trained to identify each vowel in a three-alternative forced-choice (3AFC) paradigm. The results showed that children and adults extracted vowel information at a generally high level from stimuli as brief as 10 ms. For many stimuli, there was little or no difference between the performance of children and adults. However, developmental effects were observed. First, the accuracy of vowel perception was more influenced by the consonant context for children than for adults. Whereas perception was similar across age levels for stimuli in the alveolar context, the youngest children perceived vowels in the labial and velar contexts at significantly lower levels than adults. Second, children were more affected by variations in stimulus duration than were adults. This finding was particularly prominent for the syllable [ga], where the dependency on duration decreased with age in a nearly linear fashion. These findings are discussed in relation to current hypotheses of vowel perception in adults, and hypotheses of speech perception development.

Previous research has noted a reduction in perceptual identification performance when the speaker varies from stimulus to stimulus and has interpreted this finding as an effect of a normalization process that compensates for variability in the physical content of the speech signal. The purpose of the present investigation was to examine whether the physical variability introduced by this experimental design can result in general stimulus uncertainty effects that extend beyond the realm of traditional delineations of normalization processes. The stimuli were short segments taken from nasal consonant + vowel syllables produced by 1 male adult, 1 female adult, and 2 children. Segments of 25 and 50 ms duration were edited from the nasal murmur and the onset of the vowel. The stimuli were ordered according to four variability conditions and presented to listeners for place of articulation identification. The results showed that identification was significantly reduced when variability affected either speaker identity or segment type. Further analyses revealed that segment variability impaired perception of all segment types approximately equally, but that the 50-ms vowel segments were selectively spared in the speaker variability condition. These findings indicate that general uncertainty effects should be considered in speech perception experiments, and that dynamic properties of speech are particularly important in the perceptual compensation for speaker variability.

The importance of different acoustic properties for the perception of place of articulation in prevocalic stop consonants was investigated from a developmental perspective. Eight adults and eight children in each of the age groups, 5, 6, 7, 9, and 11 years, listened to synthesized syllables comprised of all combinations of [b d g] and [i a]. The synthesis parameters were adapted from Blumstein and Stevens [J. Acoust. Soc. Am. 67, 648-662 (1980)], and included manipulations of the following stimulus variables: formant transitions (moving or straight), noise burst (present or absent), and voicing duration (10 or 46 ms). Identification performance was high for all age groups across most stimulus types. Formant transition motion generally was not necessary for accurate identification, and there was no difference between age groups in terms of the perceptual weight placed on this cue. Furthermore, the results did not support the salience of duration as a developmental cue to place of articulation. The presence of a burst improved identification for the velar and alveolar places of articulation for all age groups, but was particularly important for the 11-year-olds and adults. These findings indicate that children, by age 5, do not rely on dynamic formant motion any more than adults do, and that the ability to integrate acoustic cues across regions of spectral change shows developmental patterns.

This study investigated the level of social valence and type of social behaviors expressed in 15 children with specific language impairment as they engaged in typical language intervention activities during conversation-based and imitation-based language programs. These programs were both applied to each child over a period of several weeks. Videotapes of treatment sessions were analyzed for the presence of five verbal and 11 nonverbal behaviors selected to measure social valence. In addition, the child's level of social valence was scored on a three-point rating scale. The results showed that although both types of treatments were predominantly associated with positive social valence ratings and a high frequency of smiling, laughing, and engagement in the activities, a significantly higher number of these positive ratings and behaviors were noted within conversation-based treatment. In contrast, although negative social valence ratings and expressions of boredom or dislike were very rare, these were observed more frequently under imitation-based treatment. There was a significantly higher rate of verbal initiations in the conversation-based treatment, and a significantly higher rate of quiet, passive participation in the imitation-based treatment. The findings are discussed in relation to treatment selection and viable strategies for assessing treatment acceptability in children.