Language processes in stuttering children

Discrimination in normal children

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s):Russell D. Shilling, Robert R. Read. Includes bibliographical references (p. 117). Also available online.

Thesis (Ph. D.)--Cornell University, 1929. / "Offprinted from the American journal of psychology, October 1930, vol. XLII."

Thesis (M. Communication Pathology)--University of Pretoria, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (MTech (Elec. Eng.))--Peninsula Technikon, 2000. / Word processed copy. Summary in English. Includes bibliographical references. Also available online.

An important feature of the auditory system is its ability to distinguish many simultaneous sound sources. The primary goal of this work was to understand how a robust, preattentive analysis of the auditory scene is accomplished by the subcortical auditory system. Reasonably accurate modelling of the morphology and organisation of the relevant auditory nuclei, was seen as being of great importance. The formulation of plausible models and their subsequent simulation was found to be invaluable in elucidating biological processes and in highlighting areas of uncertainty. In the thesis, a review of important aspects of mammalian auditory processing is presented and used as a basis for the subsequent modelling work. For each aspect of auditory processing modelled, psychophysical results are described and existing models reviewed, before the models used here are described and simulated. Auditory processes which are modelled include the peripheral system, and the production of tonotopic maps of the spectral content of complex acoustic stimuli, and of modulation frequency or periodicity. A model of the formation of sequential associations between successive sounds is described, and the model is shown to be capable of emulating a wide range of psychophysical behaviour. The grouping of related spectral components and the development of pitch perception is also investigated. Finally a critical assessment of the work and ideas for future developments are presented. The principal contributions of this work are the further development of a model for pitch perception and the development of a novel architecture for the sequential association of those groups. In the process of developing these ideas, further insights into subcortical auditory processing were gained, and explanations for a number of puzzling psychophysical characteristics suggested.

Among complications associated with non-syndromic cleft lip and/or palate (NSCL/P) in school age children, conductive hearing loss has been thoroughly investigated because the symptoms are noticeable and the treatment is often easy to access. Research on central auditory processing disorder [(C)APD] has been rarely explored in this clinical population. However, children with NSCL/P have been reported to have delayed speech and language development, as well as poor academic performance in general compared to craniofacially normal peers, despite their peripheral hearing problems typically resolving with age. In order to investigate suspected (C)APD in children with NSCL/P, the present research program was initiated. The study aimed to utilize a comprehensive test battery to assess auditory status in children with NSCL/P, and to investigate whether they have a greater frequency of (C)APD compared to craniofacially normal children. 147 children with NSCL/P and 60 normal children were recruited. They were Mandarin speakers and attending regular schools. The children with NSCL/P did not have peripheral hearing problems at time of assessment. There were three types of assessment tools used in the present research program. Firstly, hearing health tests were conducted to evaluate peripheral hearing function. Case history and auditory questionnaire reports were completed by caregivers to obtain basic medical and developmental information (Chapter 3). Secondly, auditory behavioral tests of (C)APD functioning were administered, including a gap detection test and a speech in noise recognition test (Chapter 4). Thirdly, an auditory evoked potential (AEP) assessment was conducted as an objective evaluation of the central auditory nervous system (Chapter 5). Based on the results of this research program, it was concluded that, firstly, children with NSCL/P showed behaviors typically found in children with (C)APD when questionnaire results were considered. Children with cleft palate (CP) showed the most negative outcomes, and cleft lip (CL) group children showed results equivalent to craniofacially normal children. Secondly, behavioral assessment results showed that compared to control group children, maturation for temporal resolution abilities was delayed in children with NSCL/P. Also, the ability to use interaural timing and intensity cues for speech recognition in a noisy environment was poorer in children with CP and CLP. Finally, abnormal AEP findings in children with cleft suggested longer neural transmission times and delayed development of the auditory nervous system may occur in this population. In summary, the research program found that children with NSCL/P are at higher risk of auditory processing difficulties compared to craniofacially normal children. In addition, a comprehensive test battery is more appropriate for making an accurate diagnosis of (C)APD in this population than a single assessment protocol. The present research program has contributed to an enhanced awareness of potential (C)APD in children with NSCL/P, which had not been investigated using a comprehensive test battery for a large sample of children with cleft disorders in any previous studies. Since Chinese language specific assessment tools are limited, further studies to develop an appropriate, comprehensive test battery for the diagnosis of auditory processing disorder in Chinese children with oral cleft and to explore effective management of this disorder are required. / published_or_final_version / Speech and Hearing Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Speech and Hearing Sciences / Master / Master of Science in Audiology