Frequency detection of the first heart sound based on wavelet transformation / 生物医学工程学杂志

ABSTRACT

According to the valvular theory, the vibrations affected by the mitral and tricuspid valves closure in early systole produce the first heart sound (S1). S1 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 S1. First, S1 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 S1. The frequency range of this level is the major frequency range of S1. The frequency range of S1 was successfully detected by the method.