Análise do Impacto da Subtração Espectral para Tratamento de Ruído no Reconhecimento de Palavras Isoladas com Coeficiente Mel-Cepstrais

Ambientes ruidosos podem comprometer sistemas de reconhecimento de fala de modo que o sistema não consegue distinguir o ruído do sinal de voz. Neste trabalho foi analisada a eficiência da técnica de subtração espectral com retificação de meia onda para tratamento do ruído estacionário. A eficácia desta técnica foi avaliada no Framework Sphinx, levando em consideração a relação entre a taxa de reconhecimento, o nível de relação sinal-ruído e número de coeficientes Mel-cepstrais. Como resultado, observou-se que dependendo no nível de SNR, a técnica de subtração espectral suprime frequências importante do sinal, gerando o chamado ruído musical, sendo preferível permitir que o sistema utilize o sinal ruidoso

Manganese-enhanced magnetic resonance imaging detects mossy fiber sprouting in the pilocarpine model of epilepsy

Purpose: Mossy fiber sprouting (MFS) is a frequent finding following status epilepticus (SE). The present study aimed to test the feasibility of using manganese-enhanced magnetic resonance imaging (MEMRI) to detect MFS in the chronic phase of the well-established pilocarpine (Pilo) rat model of temporal lobe epilepsy (TLE). Methods: To modulate MFS, cycloheximide (CHX), a protein synthesis inhibitor, was coadministered with Pilo in a subgroup of animals. In vivo MEMRI was performed 3 months after induction of SE and compared to the neo-Timm histologic labeling of zinc mossy fiber terminals in the dentate gyrus (DG). Key Findings: Chronically epileptic rats displaying MFS as detected by neo-Timm histology had a hyperintense MEMRI signal in the DG, whereas chronically epileptic animals that did not display MFS had minimal MEMRI signal enhancement compared to nonepileptic control animals. A strong correlation (r = 0.81, p < 0.001) was found between MEMRI signal enhancement and MFS. Significance: This study shows that MEMRI is an attractive noninvasive method for detection of mossy fiber sprouting in vivo and can be used as an evaluation tool in testing therapeutic approaches to manage chronic epilepsy.FAPESP CInAPCe Program [2005/56663-1]FAPESP CInAPCe ProgramFAPESPFAPESP [07/52911-6]NIH, NINDSNIH, NIND