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Updated: Aug 14, 2026

Ultrasound-based Pulse Wave Velocity Evaluation in Mice
Published on: February 14, 2017
[Frequency detection of the first heart sound based on wavelet transformation]
1Information School, Yunnan University, Kunming 650091.
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.
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