La variabilité inter-individuelle en localisation auditive a été étudiée à travers plusieurs expérimentations. La première expérimentation a exploré la variabilité inter-individuelle en localisation auditive de sources sonores virtuelles (HRTFs individuelles et non individuelles) dans une population de 25 auditeurs naïfs préalablement soumis à un entraînement procédural. D'après nos résultats, la variabilité inter-individuelle dans la dimension gauche/droite pourrait être liée à une préférence individuelle vers un type d'indices parmi ceux utilisables pour la localisation dans cette dimension (indices binauraux/spectraux). Dans les dimensions haut/bas et avant/arrière, la variabilité inter-individuelle pourrait être liée à l'attention spatiale et à sa variation entre les zones de l'espace. Une seconde expérimentation réalisée chez les mêmes auditeurs a montré qu'une amélioration des capacités de localisation était possible par un entraînement par feedback visuel ou audio-moteur. Cette amélioration était souvent fonction de la performance avant entraînement, conduisant ainsi à une réduction de la variabilité inter-individuelle après entraînement. La variabilité inter-individuelle dans la dimension haut/bas après entraînement était en partie expliquée par l'activité du faisceau olivocochléaire efférent médian (FOCEM), structure du système auditif probablement impliquée dans le codage des indices spectraux de localisation. Ce résultat a été conforté par les résultats d'une troisième expérimentation qui ont révélé que les auditeurs dont la performance de localisation était la moins altérée dans le bruit étaient ceux dont le FOCEM avait été déterminé comme le plus actif. / Several experiments were performed to investigate interindividual variability in auditory localization. The first experiment explored interindividual variability in the localization of virtual sound sources (individualized and non-individualized HRTFs) in 25 naive listeners following procedural training. The results suggest that interindividual variability in localization performance in the left-right dimension stems from interindividual differences in the use of the different types of cues available for sound localization in this dimension (binaural/spectral cues). Interindividual variability in sound-localization performance in the up-down and front-back dimensions appears to be related primarily to spatial attention and to its variation across the area of space. A second experiment in the same group of listeners showed that localization performance can be improved by the provision of visual or auditory-motor feedback. The improvement depended upon pre-training performance, in such a way that interindividual variability in performance was smaller after training than before training. In addition, interindividual variability in the up-down dimension after training was found to be related to interindividual differences in the activity of the medial olivocochlear bundle (MOCB), an efferent auditory system that is currently likely thought to be involved in the processing of spectral cues for sound localization. This result was supported by the results of a third experiment which revealed that the listeners in whom localization performance was least impacted by background noise were those in whom the strongest MOCB had been measured.

Made available in DSpace on 2016-04-27T18:12:35Z (GMT). No. of bitstreams: 1 Fernanda Camargo Geribola.pdf: 1547941 bytes, checksum: 063b4de26b3cbb4c88109ec3946d7674 (MD5) Previous issue date: 2008-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Objective: to investigate sound localization, motor-acoustic organization and auditory discrimination performance in 7 to 11 year-old children and to describe results according to gender and to answers of teachers and parents to a questionnaire. Method: 60 children were evaluated: 30 2nd or 3rd grade students and 30 4th or 5th grade. The distribution of the students according to age was: 26,7% were 7, 21,7% were 8, 15% were 9, 35% were 10 and 1,6% were 11 years old. They were submitted to visual inspection of external acoustic meatus, pure tone audiometry, timpanometry (as an inclusion criteria). The study had three phases: screening questionnaire answered by parents, learning difficulties questionnaire answered by teachers and sound localization, motor-acoustic organization and auditory discrimination performance. Results: there was no statistically significant difference between level of scholarship and tests performance; teachers answers for the learning difficulties questionnaire and tests performance. Students who performed poorly in the tests were oral respirators, presented more ear ache and throat infection episodes, frequently asked repetition of what was said, loud speakers and had familiar history of hearing loss, according to the comparison of parents answers to a questionnaire and tests performance. Conclusions: 1. it was not possible to establish a relationship between age and tests performance; 2. learning difficulties questions for the teachers did not allow detecting students who needed auditory processing evaluation; 3. the questionnaire answered by parents allowed identifying students at risk for poor performance in the applied auditory abilities tests / Objetivo: O objetivo deste trabalho foi investigar o desempenho de crianças entre 7 e 11 anos para os testes de localização da fonte sonora, organização acústico motor e discriminação auditiva, descrevendo os resultados do desempenho das crianças nos diferentes testes em função do sexo e das respostas dos pais ao questionário. Método: Foram avaliadas 60 crianças, sendo 30 matriculadas na 2 ªou 3 ª e 30 na 4 ª ou 5 ª série, distribuídas segundo a faixa etária em : 7 anos (26,7%), 8 anos (21,7%), 9 anos (15%), 10 anos (35%) e 11 anos (1.6%). As crianças foram submetidas a inspeção visual do meato acústico externo, audiometria tonal liminar, timpanometria (como critério de inclusão). A coleta foi realizada em três fases: questionário de triagem auditiva com os pais, questionário com os professores sobre a presença de dificuldade de aprendizagem e desempenho das crianças nos testes: Teste de Localização da Fonte Sonora, de Teste de Organização Acústico-Motora e Teste de Discriminação Auditiva com as crianças. Resultados: a análise da relação entre nível de escolaridade e desempenho nos testes de não mostrou diferença estatisticamente significante. Para a questão desempenho das crianças nos diferentes testes segundo a resposta do professor para a questão ter ou não queixa de dificuldade de aprendizagem, os resultados não foram estatisticamente significantes. A análise descritiva em valores de porcentagem do desempenho das crianças nos testes aplicados em relação com às respostas dos pais ao questionário aplicado e a análise por agrupamento, mostraram que as crianças que não apresentaram desempenho adequado eram as que os pais informaram que: eram respiradores bucais, tiveram muitos episódios de dor de ouvido e infecção de garganta , falam muito Hãm e o quê; fala muito alto e devagar e que tem antecedentes familiares de perda auditiva. Conclusões: os dados obtidos nessa pesquisa permitem concluir: 1. que não foi possível estabelecer relação entre faixa etária e desempenho nos testes; 2. que a pergunta sobre dificuldade de aprendizagem feita ao professor não permite detectar crianças que necessitariam de avaliação diagnóstica de transtorno de processamento auditivo; 3. que o questionário aplicado aos pais permitiu identificar os riscos para bom desempenho nos testes de habilidades auditivas aplicados