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Thesis (M.Sc. (Computer Science)) --University of Limpopo, 2018 / The conversion of speech to text is essential for communication between speech and visually impaired people. The focus of this study was to develop and evaluate an ASR baseline system designed for normal speech to correct speech disorders. Normal and disordered speech data were sourced from Lwazi project and UCLASS, respectively. The normal speech data was used to train the ASR system. Disordered speech was used to evaluate performance of the system. Features were extracted using the Mel-frequency cepstral coefficients (MFCCs) method in the processing stage. The cepstral mean combined variance normalization (CMVN) was applied to normalise the features. A third-order language model was trained using the SRI Language Modelling (SRILM) toolkit. A recognition accuracy of 65.58% was obtained. The refinement approach is then applied in the recognised utterance to remove the repetitions from stuttered speech. The approach showed that 86% of repeated words in stutter can be removed to yield an improved hypothesized text output. Further refinement of the post-processing module ASR is likely to achieve a near 100% correction of stuttering speech Keywords: Automatic speech recognition (ASR), speech disorder, stuttering

Stuttering has been a complex problem ever since the early history of man. It has been found to exist in some cultures to a greater extent than in others. In certain primitive cultures the phenomenon of stuttering was reported to be unknown, yet when members of these cultures were influenced by western environments some incidence of stuttering occurred among them. The influence of the environment therefore cannot be disregarded when considering causes of stuttering. Although much research has been done by speech pathologists among various world cultures they have by no means completed their task for there are many groups, living in a variety of societies, which are yet to be studied. The present rudimentary investigation into stuttering among Indians living in Durban may be regarded as a contribution to the knowledge that has already been accumulated. / Thesis (M.A.)-University of Natal, Durban, 1971.

This thesis presents thirteen research papers published between 1987-97, and a summary and discussion of their contribution to the field of developmental speech disorders. The publications collectively constitute a body of work with two overarching themes. The first is methodological: all the publications report articulatory data relating to tongue movements recorded using the instrumental technique of electropalatography (EPG). The second is the clinical orientation of the research: the EPG data are interpreted throughout for the purpose of informing the theory and practice of speech pathology. The majority of the publications are original, experimental studies of lingual articulation in children with developmental speech disorders. At the same time the publications cover a broad range of theoretical and clinical issues relating to lingual articulation including: articulation in normal speakers, the clinical applications of EPG, data analysis procedures, articulation in second language learners, and the effect of oral surgery on articulation. The contribution of the publications to the field of developmental speech disorders of unknown origin, also known as phonological impairment or functional articulation disorder, is summarised and discussed. In total, EPG data from fourteen children are reported. The collective results from the publications do not support the cognitive/linguistic explanation of developmental speech disorders. Instead, the EPG findings are marshalled to build the case that specific deficits in speech motor control can account for many of the diverse speech error characteristics identified by perceptual analysis in previous studies. Some of the children studied had speech motor deficits that were relatively discrete, involving, for example, an apparently isolated difficulty with tongue tiplblade groove formation for sibilant targets. Articulatory difficulties of the 'discrete' or specific type are consistent with traditional views of functional lingual articulation in developmental speech disorders articulation disorder. EPG studies of tongue control in normal adults provided insights into a different type of speech motor control deficit observed in the speech of many of the children studied. Unlike the children with discrete articulatory difficulties, others produced abnormal EPG patterns for a wide range of lingual targets. These abnormal gestures were characterised by broad, undifferentiated tongue-palate contact, accompanied by variable approach and release phases. These 'widespread', undifferentiated gestures are interpreted as constituting a previously undescribed form of speech motor deficit, resulting from a difficulty in controlling the tongue tip/blade system independently of the tongue body. Undifferentiated gestures were found to result in variable percepts depending on the target and the timing of the particular gesture, and may manifest as perceptually acceptable productions, phonological substitutions or phonetic distortions. It is suggested that discrete and widespread speech motor deficits reflect different stages along a developmental or severity continuum, rather than distinct subgroups with different underlying deficits. The children studied all manifested speech motor control deficits of varying degrees along this continuum. It is argued that it is the unique anatomical properties of the tongue, combined with the high level of spatial and temporal accuracy required for tongue tiplblade and tongue body co-ordination, that put lingual control specifically at risk in young children. The EPG findings question the validity of assumptions made about the presence/absence of speech motor control deficits, when such assumptions are based entirely on non-instrumental assessment procedures. A novel account of the sequence of acquisition of alveolar stop articulation in children with normal speech development is proposed, based on the EPG data from the children with developmental speech disorders. It is suggested that broad, undifferentiated gestures may occur in young normal children, and that adult-like lingual control develops gradually through the processes of differentiation and integration. Finally, the EPG fmdings are discussed in relation to two recent theoretical frameworks, that of psycho linguistic models and a dynamic systems approach to speech acquisition.

A thesis submitted in fulfilment of the requirement for the degree of Doctor of Philosophy, Faculty of Humanities; University of the Witwatersrand. June 2016 / This study explored the experiences of and interactions between speech-language therapists and interpreters in cross-linguistic mediated consultations with caregivers of children with severe disabilities within a health care setting. The objectives of the study included: to analyse the interactional characteristics and features of speech-language therapists and interpreters; and to identify speech therapists’ and interpreters’ perceptions of their competence and experiences in multicultural settings. Patients who do not speak the same language as the health care professionals receive limited health services when compared with people who speak the same language as the professionals who serve them, which may result in poor health outcomes. The research was conducted from an interpretive approach, which includes a respect for intra- personal values, beliefs and interests in the topic. The design included multiple data collection methods and analysis. The data was collected from consultation experience of thirteen caregivers of children with communication disabilities, five SLTs and one interpreter in two urban hospitals in Gauteng. The participants were recruited using purposive sampling procedures from two urban tertiary hospitals in Gauteng. And group Research instruments used were video recordings, individual interviews. The objectives were investigated through a qualitative study using ethnographic observations; video recordings of the interactions between speech therapists and an interpreter during interviews with caregivers of children with disabilities; audio recordings; and individual interviews with speech-language therapists and interpreters post-consultation. The data collected were analysed using thematic content analysis and conversational analysis. The findings highlighted the diversity challenges faced by SLTs working in multilingual and multicultural hospital settings. Language and translation issues had a marked impact on information received by caregivers. Despite the challenges that clinicians experienced in multilingual settings, they seemed to find that their working experience was an important leveller when they had an interpreter present during their consultations. The findings inform academic curricula and the clinical practice of speech-language and audiology students and professionals and will help improve application to transform the way in which they apply theoretical knowledge when treating speech and hearing disorders in a multilingual and multicultural context; thus enhancing the efficacy of management of communication disorders within this context. / MT 2018

Researchers have used electroencephalography (EEG) as a window into the activities of the brain. High temporal resolution coupled with relatively low cost compares favourably to other neuroimaging techniques such as magnetoencephalography (MEG). For many years silver metal electrodes have been used for non-invasive monitoring electrical activities of the brain. Although these electrodes provide a reliable method for recording EEG they suffer from noise, such as offset potentials and drifts, and usability issues, e.g. skin prepa- ration and short circuiting of adjacent electrodes due to gel running. Low frequency noise performance is the key indicator in determining the signal to noise ratio of an EEG sensor. In order to tackle these issues a prototype Electric Potential Sensor (EPS) device based on an auto-zero operational amplifier has been developed and evaluated. The absence of 1/f noise in these devices makes them ideal for use with signal frequencies ~10Hz or less. The EPS is a novel active electrode electric potential sensor with ultrahigh input impedance. The active electrodes are designed to be physically and electrically robust and chemically and biochemically inert. They are electrically insulated (anodized) and scalable. These sensors are designed to be immersed in alcohol for sterilization purposes. A comprehensive study was undertaken to compare the results of EEG signals recorded by the EPS with different commercial systems. These studies comprised measurements of both free running EEG and Event Related Potentials. Strictly comparable signals were observed with cross correlations of higher than 0.9 between the EPS and other systems.

Researchers are seeking more information . on how and why language disorders tend to run in families, particularly siblings of language disordered children. The purpose of this study was to examine the prevalence of language and related disorders in the siblings of two groups of children: those with slow expressive language development (SELD) and those with a normal language history. This study sought to answer the following questions: 1) Is there a significant difference in prevalence of language problems in two groups of children: those with SELD and those with a normal language history?, and 2) Is there a greater probability of language problems in the siblings of children in the SELD group who have receptive/expressive language disorders when compared to those SELD children with pure expressive language deficits or to those with a normal language history? Subjects were 45 7-and 8-year old children participating in a longitudinal study at Portland State University. The children were divided into two groups, normal and SELD, based on test scores administered at intake to the original study. In order to look at the effect of a receptive component on heritability of language disorders, the SELD group was subgrouped into pure expressive language disorders and receptive/expressive language disorders based on tests administered at intake. A family history questionnaire was the method of data collection, asking parents to report on ten areas of language and related disorders in the siblings of subjects. Results of one-sided z-tests and a chi-square test were computed and consistently found a highly significant difference between groups, with families of SELD subjects more likely to report a history of language problems over the normal group. These results are consistent with previous research in showing the heritability of language disorders. Results may also indicate that a receptive language component is associated with heritability of specific language disorders among children.

The process of differentially diagnosing a child who is experiencing temporary normal disfluency from one who is beginning to stutter could be made objective by the establishment of normative data on fluency development. To date, there are no standardized norms on the development of fluency in children. Current investigations have contributed greatly to expectations of certain types and amounts of disfluencies in preschool-age children. Most of the research, however, has focused on observing children at discrete age levels from 2- to 7-years-of-age. Only one longitudinal study to date has been reported. Additional longitudinal data of preschoolaged children would benefit the establishment of normative data. Observing the same children over time helps to expose the subtleties that could be missed when looking only at specific age levels. The present study sought to contribute to the investigation of normal childhood disfluency by comparing various types and amounts of disf luencies in 44- to 49-month-old-children to the results of the same group of children when they were 30- to 35-months-of-age.

Speech-language pathologists are constantly trying to use the most efficient and effective assessments to obtain information about the phonetic inventory, speech sound errors, and phonological error patterns of children who are suspected of having a speech sound disorder. These assessments may involve a standardized measure of single words and/or sentences and a non standardized measure, such as a spontaneous speech sample. While research has shown both of these types of assessments to give clinicians information about a child's speech production abilities, the use of delayed imitation tasks, either words or sentences, has not been a widely studied topic and has produced conflicting results when researched. The purpose of the present study was to examine speech sound production abilities in children with a speech sound disorder in a single-word task, an imitated sentence task, and spontaneous speech sample to compare their results of speech sound errors, phonological error patterns, and time administration. The study used the Phonological and Articulatory Bilingual Assessment - English version (PABA-E, Gildersleeve-Neumann , 2008), a formal assessment for identifying children who may have a speech sound disorder. Three male children, between the ages of 4;0 and 5;4 (years;months), participated in this study. All participants were being treated by a speech-language pathologist for a diagnosed speech sound disorder and had hearing within normal limits. The results of the study showed that the majority of participants produced the highest number of speech sounds targeted within the imitated sentence task. Participants attempted and produced the least amount of speech sounds on their spontaneous speech sample. The assessment with the highest percentage of accurately produced consonants was the imitated sentence task. The majority of participants produced a higher number of error patterns in their single-word and imitated sentence task. In terms of efficiency and effectiveness, the imitated sentence task took the least amount of time to administer and transcribe.

Thesis (M.Communication Pathology) -- University pf Pretoria, 2000. / Summary in English and Afrikaans.