Processing of English words with fine acoustic contrasts and simple tones: A mismatch negativity study

The purpose of this study was to compare the robustness of the event-related potential (ERP) response, called the mismatch negativity (MMN), when elicited by simple tone stimuli (differing in frequency, duration, or intensity) and speech stimuli (CV nonword contrast /de:/ vs. /ge:/ and CV word contrast /deI/ vs. /geI/). The study was conducted using 30 young adult subjects (Groups A and B; n = 15 each). The speech stimuli were presented to Group A at a stimulus onset asynchrony (SOA) of 610 msec and to Group B at an SOA of 900 msec. The tone stimuli were presented to both groups at an SOA of 610 msec. MMN responses were elicited by the simple tone stimuli (66.7%-96.7% of subjects with MMN "present," or significantly different from zero, p < 0.05) but not the speech stimuli (10% subjects with MMN present for nonwords, 10% for words). The length of the SOA (610 msec or 900 msec) had no effect on the ability to obtain consistent MMN responses to the speech stimuli. The results indicated a lack of robust MMN elicited by speech stimuli with fine acoustic contrasts under carefully controlled methodological conditions. The implications of these results are discussed in relation to conflicting reports in the literature of speech-elicited MMNs, and the importance of appropriate methodological design in MMN studies investigating speech processing in normal and pathological populations.

Visual-auditory integration during speech imitation in autism

Children with autistic spectrum disorder (ASD) may have poor audio-visual integration, possibly reflecting dysfunctional 'mirror neuron' systems which have been hypothesised to be at the core of the condition. In the present study, a computer program, utilizing speech synthesizer software and a 'virtual' head (Baldi), delivered speech stimuli for identification in auditory, visual or bimodal conditions. Children with ASD were poorer than controls at recognizing stimuli in the unimodal conditions, but once performance on this measure was controlled for, no group difference was found in the bimodal condition. A group of participants with ASD were also trained to develop their speech-reading ability. Training improved visual accuracy and this also improved the children's ability to utilize visual information in their processing of speech. Overall results were compared to predictions from mathematical models based on integration and non-integration, and were most consistent with the integration model. We conclude that, whilst they are less accurate in recognizing stimuli in the unimodal condition, children with ASD show normal integration of visual and auditory speech stimuli. Given that training in recognition of visual speech was effective, children with ASD may benefit from multi-modal approaches in imitative therapy and language training. (C) 2004 Elsevier Ltd. All rights reserved.

The epidemiology of dysphagia: Describing the problem - are we too late?

The assessment and management of dysphagia is a rapidly growing part of speech pathology clinical practice for both adult and paediatric populations, yet there is limited information available regarding the epidemiology of dysphagia. Very few studies have defined the characteristics of the disorder, its incidence/prevalence in various populations, the natural history of the disorder or the relative risks, comorbidities and outcomes associated with dysphagia. The current paper will identify some fundamental questions that as yet remain unanswered and highlight areas of future research that are required in order for us to have a better understanding of dysphagia and inform assessment and management. In conclusion, the authors propose an epidemiological framework and highlight information needs in the field of dysphagia. This framework urges future dysphagia research to be informed and underpinned by sound epidemiological principles.

Articulatory function in hypokinetic dysarthria: An electropalatographic examination of two cases

The present study employed electropalatography (EPG) and a nonspeech measure of lingual function to examine, in detail, the articulatory production deficits of two individuals with Parkinson disease (PD) and hypokinetic dysarthria. Participants read 10 repetitions of CV words contained within the carrier phrase I saw a _ today while wearing an EPG artificial palate. Target consonants included the alveolar stop /t/, lateral approximant /l/, and the alveolar fricative /s/ in the /a/ vowel environment. The results of the two participants were compared to an age-matched control group. Examination of the perceptual features of articulatory production, lingual strength, fine force control and endurance, tongue-palate contact patterns, and segment durations were conducted. Results of the study revealed quite different articulatory deficits in the two participants. Specifically, the articulation of Participant One (P1) was characterized by a fast rate of speech, undershooting of articulatory targets, and reduced duration of consonant closures. In contrast, Participant Two (P2) demonstrated tongue-palate contact patterns indicative of impaired lingual control in the presence of both normal and increased articulatory segment durations. Potential reasons for the differing articulatory deficits were hypothesized. The current study demonstrated that assessment with EPG identified potential causes of consonant imprecision in two individuals with hypokinetic dysarthria. Directions for speech pathology intervention, salient from the results of the study, were also noted.

Use of electropalatography in the treatment of disordered articulation following traumatic brain injury: A case study

Electropalatography (EPG) was used as a biofeedback tool in a case study of a 30-year-old male with disordered articulation following traumatic brain injury (TBI). Based on qualitative measures of the participant's intelligibility, improved articulation of the fricatives /s/ and /integral/ were selected as treatment targets. Therapy was administered three times a week for 5 weeks. Results showed that word and sentence intelligibility increased approximately 10%, and error patterns for lingual articulation indicated that fricative -> stop and other fricative errors decreased considerably. EPG measures for /s/ exhibited a significantly more anterior main focus of articulatory contact post therapy. Consonant durations were significantly longer during weeks 3 and 4, and this finding was associated with the emergence of an articulatory contact pattern with a groove rather than complete closure. This articulatory pattern appeared inconsistently and was found to vary across articulations of /s/ but also within a single consonant production. For /integral/, the amount of contact was significantly reduced post therapy and an increase in duration was noted during week 4, similar to that occurring in the production of /s/. Spatial and timing measures were more variable than in normal speakers of English and indicated a general increase in variability across weeks for both /s/ and /integral/. It was concluded that, although the correct fricative patterns appeared only intermittently during production of the consonants, there seemed to be sufficient information for the listener to be able to classify the sound as a fricative. As a part of an intervention program, visual EPG biofeedback therapy would appear to have a definite role in assisting dysarthric speakers exhibiting difficulties with lingual articulation in understanding their errors, learning how to exploit kinesthetic, and acoustic sources of feedback, and how to make appropriate adjustments in tongue articulation to increase the level of speech intelligibility.

Aphasia websites: An examination of their quality and communicative accessibility

Background: Studies have examined Internet use as a source of information by various populations, however no study has examined the quality and accessibility of websites for people with aphasia, or their use of such sites. Aims: This study aimed to describe the quality, communicative accessibility, and readability of a sample of aphasia websites and to determine whether sites preferred by people with aphasia were those rated highly on measures of accessibility and quality. The perceptions of people with aphasia regarding the accessibility of the sites were compared with those of speech pathologists. The relationship between the quality and communicative accessibility of websites was analysed. Factors that may influence use of the Internet by people with aphasia and speech pathologists were explored. Methods & Procedures: Tools for measuring quality and communicative accessibility were developed and a sample of five websites was selected. Two participant groups (18 speech pathologists and 6 people with aphasia) assessed aphasia websites in terms of communicative accessibility. Speech pathologists also rated website quality. Spearman's rho was used to determine levels of agreement between variables. Outcomes & Results: People with aphasia and speech pathologists showed minimal agreement on their perceptions of communicative accessibility. However, when the preferences of websites (Aphasia Help and Speakability) were of a very high standard. There was a weak relationship between quality and communicative accessibility, however it was not statistically significant. Conclusions: Accessible websites are not necessarily of high quality, and quality websites are not guaranteed to be easily accessible. People with aphasia did not agree with speech pathologists as to what makes a good aphasia website. Therefore, people with aphasia should be involved in the design of aphasia websites since they are often the intended users. If Internet use by people with aphasia increases in line with other health populations, speech pathologist need to have the skills and confidence to recommend appropriate sites to their clients.

Top-down influences on lexical selection during spoken word production: A 4T fMRI investigation of refractory effects in picture naming

Spoken word production is assumed to involve stages of processing in which activation spreads through layers of units comprising lexical-conceptual knowledge and their corresponding phonological word forms. Using high-field (4T) functional magnetic resonance imagine (fMRI), we assessed whether the relationship between these stages is strictly serial or involves cascaded-interactive processing, and whether central (decision/control) processing mechanisms are involved in lexical selection. Participants performed the competitor priming paradigm in which distractor words, named from a definition and semantically related to a subsequently presented target picture, slow picture-naming latency compared to that with unrelated words. The paradigm intersperses two trials between the definition and the picture to be named, temporally separating activation in the word perception and production networks. Priming semantic competitors of target picture names significantly increased activation in the left posterior temporal cortex, and to a lesser extent the left middle temporal cortex, consistent with the predictions of cascaded-interactive models of lexical access. In addition, extensive activation was detected in the anterior cingulate and pars orbitalis of the inferior frontal gyrus. The findings indicate that lexical selection during competitor priming is biased by top-down mechanisms to reverse associations between primed distractor words and target pictures to select words that meet the current goal of speech.

Treating the speech disorder in Parkinson's Disease Online

The Lee Silverman Voice Treatment (LSVT) has been shown to be highly effective in treating the speech disorder in Parkinson's Disease (PD). However, patient access to this treatment remains limited in Australia, due to availability of speech pathologists, patient mobility and distance issues. We have investigated the feasibility and effectiveness of an Internet-based telerehabilitation application (eREHAB) for the delivery of the LSVT to persons with PD and disordered speech. Ten participants with PD and dysarthria were treated online with the LSVT for a total of 16 sessions. There were significant improvements in sound pressure levels for vowel prolongation, reading and conversational monologue (P < 0.01), pitch range (P < 0.05) and in perceptual features of pitch and loudness variability, loudness level (P < 0.01) and breathiness (P < 0.05). A participant satisfaction questionnaire indicated that 70% of participants expressed overall satisfaction with the online treatment. Telerehabilitation was feasible and effective in delivering the LSVT to people with PD.

A participatory design agenda for ubiquitous computing and multimodal interaction: A case study of dental practice

This paper reflects upon our attempts to bring a participatory design approach to design research into interfaces that better support dental practice. The project brought together design researchers, general and specialist dental practitioners, the CEO of a dental software company and, to a limited extent, dental patients. We explored the potential for deployment of speech and gesture technologies in the challenging and authentic context of dental practices. The paper describes the various motivations behind the project, the negotiation of access and the development of the participant relationships as seen from the researchers' perspectives. Conducting participatory design sessions with busy professionals demands preparation, improvisation, and clarity of purpose. The paper describes how we identified what went well and when to shift tactics. The contribution of the paper is in its description of what we learned in bringing participatory design principles to a project that spanned technical research interests, commercial objectives and placing demands upon the time of skilled professionals. Copyright © 2010 ACM, Inc

Linguistic determinism and theory of mind in deaf children

DeVilliers and DeVilliers (2000, 2005) propose that deaf and hearing children acquire a theory of mind (or the understanding that human behaviour is the product of psychological states like true and false beliefs) as a consequence of their linguistic mastery of a rule of syntax. Specifically, they argue that the syntactic rule for sentential complementation with verbs of speech (e.g., “say”) precedes syntactic mastery of complementation for cognition (e.g., “think”) and both of these developmentally precede and promote conceptual mastery of a theory of mind (ToM), as indexed via success on standard false belief tests. The present study examined this proposition in groups of primary-school-aged deaf children and hearing preschoolers who took false belief tests and a modified memory for complements test that included control questions. Guttman scaling techniques indicated no support either for the prediction that syntactic skill precedes ToM understanding or for the earlier emergence of complementation for “say” than for “think”. Methodological issues and implications for deaf children's ToM development are discussed.