数字滤波对脑电功率谱影响的研究

Experimeutol Study on the Effects of Digital Filter on Electroencephal Ographic Power Spectrum

采用二阶、四阶、八阶递归数字滤波软件，使用不同的滤波参数，对２．０～２０．０Ｈｚ的１００条脑电曲线进行试验研究。结果为：各阶滤波均对功率谱曲线的幅值有明显影响；四阶以上显示显著性差异；各阶波滤对δ频带的频率有明显影响；滤波阶次越高，则其影响越大；同一频带改变量百分比的标准差较大，即离散度大，尚无法校正；数字滤波技术在脑电地形图诊断中应用尚存在明显缺陷。提出了使用数字滤波时的弥补措施。

One hundred electroencephal ographic curves with the frequency between 2.0 Hi and. 20.0 Hzhave been studied by using the second, fourth and eighth rank recurring digital filter with different factors.The conclusions are: the fourth and eighth rank filters present a remarkable difference in the effect on thepeaks of the power spectrum, while the second presents an apparent effect.For & band, all ranks have greateffects and the higher the rank is, the greater the effect.The standard difference of the variation percentageof the peak in one band,is relatively great,namely,the dispersed ratio is great, and cann't be corrected yet.So,using digital filter still exists evident defects in the diagnosis of brain electrical activity mapping.Theremedy method is put forward in this paper when using digital filter.