Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 114-121).

Thesis (M. (Communication Pathology))--University of Pretoria, 2005. / Includes bibliographical references.

Thesis--University of Jyväskylä, 1997. / Added t.p. with thesis statement inserted.

Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2008. / A thesis submitted for the degree of Doctorate of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 98-133)

Orientador: Ana Claudia Figueiredo Frizzo / Banca: Ana Cláudia Vieira Cardoso / Banca: Pedro de Lemos Menezes / Resumo: Introdução: O Potencial Evocado Auditivo de Tronco Encefálico analisa a resposta eletrofisiológica gerada pelo sincronismo das estruturas da via auditiva. Ao considerar o aumento da expectativa de vida da população e a dificuldade de comunicação, verificou-se a necessidade de investigar e conhecer a dinâmica e a função auditiva central nos idosos. Objetivo: Descrever e comparar os potenciais evocados auditivos de tronco encefálico em jovens e idosos com estimulação monoaural e binaural, em duas situações de escuta, com e sem ruído competitivo. Metodologia: Estudo analítico, observacional e transversal. Realizado procedimento de pré-coleta composto por entrevista, avaliação audiológica básica e mini exame do estado mental. Participaram 20 idosos, de ambos os gêneros, a partir de 60 anos, com limiares auditivos dentro da normalidade ou com perda auditiva neurossensorial leve e 10 jovens, de ambos os gêneros, com limiares auditivos dentro da normalidade. Para a coleta de dados, o potencial foi registrado com equipamento Biologic's de dois canais, estimulação monoaural e intensidade de 80 dBNA; o mesmo foi realizado com ruído competitivo em 70 dBNA. Por último, foi realizada pesquisa com estímulo binaural e cálculo do componente de integração binaural. Resultados: Foi realizada a análise e comparação das respostas obtidas com a estimulação monoaural e binaural nas situações de escuta, com e sem ruído competitivo nos dois grupos. No registro ipsilateral houve diferenças na latênci... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction: The Auditory Evoked Potential of the Brain Stem analyzes the electrophysiological response generated by the synchronization of auditory pathway structures. When considering the increase in the life expectancy of the population and the difficulty of communication, it was verified the need to investigate and to know the dynamics and the central auditory function in the elderly. Objective: To describe and compare brainstem auditory evoked potentials in young and old with monaural and binaural stimulation in two listening situations, with and without competitive noise. Methodology: Analytical, observational and transversal study. Performed pre-collection procedure consisting of interview, basic audiological evaluation and mini mental state examination. Twenty elderly individuals of both genders, aged 60 years and older, with auditory thresholds within normal range or with mild sensorineural hearing loss, and 10 young adults, of both genders, with auditory thresholds within normal range, participated. For the data collection, the potential was recorded with Biologic's two-channel equipment, monaural stimulation and intensity of 80 dBNA; The same was done with competitive noise at 70 dBNA. Finally, a research with binaural stimulus and calculation of the binaural integration component was performed. Results: We performed the analysis and comparison of the responses obtained with monaural and binaural stimulation in listening situations, with and without competitive no... (Complete abstract click electronic access below) / Mestre

No description available.

This research investigated the effects of age, sex, male vs female voice, and unfamiliar vs familiar voice upon the infants body movements. The sample consisted of 40 middle-class infants, balanced according to sex, at four age levels -- 3, 6, 9, 12 months. Four tape-recorded stimulus conditions -- mother's voice, father's voice, female stranger’s voice, and male stranger's voice -- were presented to each infant. The body movements of the infants were recorded at one frame per second by an 8mm. camera. Analyses of variance were performed to determine any differences among the four stimulus conditions and control periods. The 12-month-old infants showed more activity to the father's voice than to the male stranger's voice or to the mother's voice. These subjects also showed more activity to the female stranger's voice than to the male stranger's voice. Female subjects were more active than male subjects to the unfamiliar voices on Trial 1. On Trial 2 females showed greater activity than males to the familiar voice. Females exhibited greater activity than males overall. Males showed greater activity than females to the cessation of the female voice and to the initiation of their father's voice. Results were discussed in terms of the infant's development as affected by sex of the infant and the cross-over effect found by Friedlander (1970). / Master of Science

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

Individual differences in learning with a focus on neuropsychologic anomalies underlying learning strategies has been receiving attention in recent years. As a result, interest has increased in quantifying and analyzing cognitive behavior more directly. One of the tools that measures brain activity directly is the evoked potential (EP). This study investigated the EP recorded from the brainstem region, often referred to as brainstem auditory evoked response (BAER). The importance of BAERs in detecting pathology in the brainstem has been well documented. BAERs have also been advocated as an important tool in the electrophysiological assessment of children's brainstem function relative to learning disorders. BAER latencies were recorded, therefore, from a small group of average children and studied in relation to the BAER stability overtime. Intra-individual differences were compared to between-subject differences. So little BAER research has been performed with children that more studies are needed just to clarify normal variability of BAER parameters. The present investigation studied intra-individual differences in the stability of BAER latencies over time in young subjects with normal hearing, for comparing with and contrasting to previous results from a study using an adult sample. BAER latencies were recorded for left, right, and binaural ear presentations. A coefficient of stability (CS) was calculated for each peak, for each ear over time. ANOVA results showed significance for peak and peak by ear interaction. Several BAER parameters were examined within-subjects that may not be revealed in studies between-subjects. Profiles for intra-aural differences over time showed individual differences in the stability of the BAER. Although there appeared to be a trend toward inter-ear differences the differences did not reach significance. The profiles indicated considerable intra-aural pattern replicability, and a trend toward increase in stability over time. The results supported a need for future research on laterality studies, more age specific normative data and correlational studies in relation to individual cognitive differences.

The mature central nervous system (CNS) has the capacity to reorganise when there is a change in sensory input. However, studies using the N1 cortical auditory evoked potential, or its magnetic homolog N1m, have not consistently demonstrated evidence of plasticity in adults with late onset unilateral deafness. In addition, little is known about the time course of experience-related plasticity in adults with unilateral deafness. The aim of the studies described in this thesis was to investigate plasticity in adults with unilateral deafness, using N1 auditory evoked potentials. Deafness occurred as a result of surgery for the removal of an acoustic neuroma. The stimuli were 500-Hz and 4-kHz tones presented monaurally to the intact ear, and the data were analysed using global field power and dipole source analysis. In the first study (Chapter 3), hemispheric asymmetries in the N1 response were measured in a group of 24 normally hearing adults at presentation levels of 40, 60 and 80 dB sensation level (SL). The results revealed that the mean hemispheric asymmetry was greater for the 4-kHz stimulus but there was no significant effect of presentation level. In addition, the results revealed that the magnitude of hemispheric asymmetry depended on the ear of stimulation; a trend for larger asymmetries was observed following stimulation of the left ear. The results of the study provide confidence that the methodology is suitable for measuring hemispheric asymmetries in individuals with unilateral deafness. The effect of stimulus level is important since this will vary in plasticity studies involving individuals with late onset unilateral deafness due to their pure tone sensitivity thresholds. Clarifying the effect of stimulus frequency in normally hearing adults is important since the effect of stimulus frequency on plasticity following unilateral deafness has not been reported previously.In the second study (Chapter 4), N1 responses were measured in 19 adults with unilateral deafness (10 and 9 right- and left-sided deafness respectively). Stimuli were typically presented at 60 dB SL. The results revealed that there was significantly greater mean activity and a shift towards reduced hemispheric asymmetries compared with 19 audiogram-matched controls. Similar changes were apparent after both right- and left-sided deafness, and for both 500-Hz and 4-kHz stimuli. Therefore the results reveal evidence of experience-related plasticity that mirrors the findings reported in animal models. The reduced hemispheric asymmetries were reflected in the dipole source model used in this thesis by changes in dipole strength, location and orientation. These findings may explain the inconsistencies reported in previous studies that have used N1 or N1m, where dipole location and orientation have not always been taken into adequate consideration.In the third study (Chapter 5), longitudinal measurements were made in six adults just prior to the onset of complete unilateral deafness, and at 1-, 3- and 6-months after the onset (4 right-sided and 2 left-sided deafness respectively). The results from the second study were further analysed by splitting the data into two groups: nine participants with <2 years deafness and 10 with ≥2 year's deafness. The results from the longitudinal data revealed that there was a significant difference in mean activity across the four conditions. For both stimulus types an increase in mean activity occurred after the onset of deafness, and hemispheric asymmetries were reduced. The biggest changes occurred within 1-month, although further increases were noted in some individuals with ≥2 year's duration of deafness. Changes that continue over this period of time suggest different physiological mechanisms for plasticity within the human central auditory system.