Arnott P J, Pfeiffer G W, Tavel M E
J Biomed Eng. 1984 Apr;6(2):121-8. doi: 10.1016/0141-5425(84)90054-2.
Frequency analysis of heart sounds has been gaining recognition as a possible indicator of several heart and valve diseases, although a comprehensive study of normal heart sounds has not been published. Relating the frequency content of normal heart sounds to certain physical characteristics surrounding the generation of these sounds could lead to a valuable diagnostic tool and give a better understanding of the mechanism of heart sounds production. In this study, the first and second heart sounds from seventy-four normal, and seven hypertensive volunteers were recorded, digitized and analysed using a Fast Fourier Transform algorithm. Statistical analysis was used to relate physical characteristics (sex, blood pressure, and body surface area) of the subjects to the frequency content of normal heart sounds and to compare normal and hypertensive heart sounds. Statistical analysis showed that the major concentration of energy, for both first heart sound (S1) and second heart sound (S2), is below 150 Hertz (Hz) which may indicate that both sounds are caused by vibrations within the same structure, possibly the entire heart. However S2 spectra have greater amplitude than S1 spectra above 150 Hz, which may be due to vibrations within the aorta and pulmonary artery. Relationships observed between body surface area, sex, blood pressure, and the frequency content of heart sounds indicate that as heart size increases, the amplitude of the frequency coefficients above 150 Hz decreases. These observations were more identifiable in the S1 spectra than in the S2 spectra, possibly because the S2 higher frequency components may mask subtle changes in the S2 spectra caused by heart size changes. However, when the changes in heart size are significant, as in hypertension or increased body surface area, trends in the S2 spectra can be observed.
心音的频率分析作为多种心脏和瓣膜疾病的一种可能指标，已逐渐得到认可，尽管尚未发表关于正常心音的全面研究。将正常心音的频率成分与产生这些声音的某些身体特征联系起来，可能会产生一种有价值的诊断工具，并能更好地理解心音产生的机制。在本研究中，记录了74名正常志愿者和7名高血压志愿者的第一心音和第二心音，使用快速傅里叶变换算法进行数字化处理和分析。采用统计分析将受试者的身体特征（性别、血压和体表面积）与正常心音的频率成分相关联，并比较正常心音和高血压心音。统计分析表明，第一心音（S1）和第二心音（S2）的主要能量集中在150赫兹（Hz）以下，这可能表明两种声音都是由同一结构内的振动引起的，可能是整个心脏。然而，在150 Hz以上，S2频谱的幅度比S1频谱大，这可能是由于主动脉和肺动脉内的振动所致。观察到的体表面积、性别、血压与心音频率成分之间的关系表明，随着心脏大小的增加，150 Hz以上频率系数的幅度减小。这些观察结果在S₁频谱中比在S₂频谱中更明显，可能是因为S₂的高频成分可能掩盖了心脏大小变化引起的S₂频谱中的细微变化。然而，当心脏大小变化显著时，如在高血压或体表面积增加的情况下，可以观察到S₂频谱的趋势。
