Lim K O, Boughner D R, Hui P W, Lee M
Jpn Heart J. 1984 May;25(3):293-9. doi: 10.1536/ihj.25.293.
Each sound signal of the first and the second heart sounds of humans was divided into three equal segments. The frequency spectrum of each segment was analyzed using the fast-Fourier-transform technique. Theory predicts that if the first and second heart sounds are caused principally by the respective vibrations of the atrioventricular and semilunar valves, then the frequency of these sounds should increase with an increase in the pressure difference across these valves. In other words, the frequency of the heart sounds should increase with time, as the pressure difference across these valves increases with time for most of the duration of the sounds. Our frequency analysis, however, showed that there is no systematic relation between the predominant frequency of successive segments of the sound signals. This therefore appears to indicate that it is quite unlikely that the vibrations of the heart valves are the principal contributor to the origin of the first and second heart sounds.
人类第一心音和第二心音的每个声音信号都被分成三个相等的部分。使用快速傅里叶变换技术对每个部分的频谱进行分析。理论预测，如果第一心音和第二心音主要是由房室瓣和半月瓣各自的振动引起的，那么这些声音的频率应该随着这些瓣膜两端压差的增加而增加。换句话说，心音的频率应该随着时间增加，因为在声音的大部分持续时间内，这些瓣膜两端的压差会随着时间增加。然而，我们的频率分析表明，声音信号连续部分的主导频率之间没有系统的关系。因此，这似乎表明心脏瓣膜的振动很不太可能是第一心音和第二心音产生的主要原因。
