基于小波变换的第一心音频率检测

Frequency Detection of the First Heart Sound Based on Wavelet Transformation

根据心脏瓣膜收缩原理 ,第一心音 (S1 )是在心脏收缩期由二尖瓣和三尖瓣关闭时引起的振动产生的 ,含有多个频率分量。本文介绍一种利用小波变换的多分辨分析原理确定 S1 频率范围的方法。首先将 S1 按频率分解成不同的层 ,然后计算各层的规一化香农能量 ,具有最大规一化香农能量的层 ,即为 S1 的主要成分集中层。该层的频率范围就是 S1 的主要频率范围。这一方法成功地确定出了 S1 的频率范围。

According to the valvular theory, the vibrations affected by the mitral and tricuspid valves closure in early systole produce the first heart sound (S 1). S 1 usually includes many frequency components. In this paper, a method using the multi-resolution analysis of wavelet transformation is recommended for detecting the frequency range of S 1. First, S 1 was decomposed into different levels on frequency. Then the normalized Shannon energy of the different levels was calculated. The level containing the maximum energy is the major components' level of S 1. The frequency range of this level is the major frequency range of S 1. The frequency range of S 1 was successfully detected by the method.