Origin of heart sounds. Results of frequency analytical studies on heart sounds

Abstract

Applying mathematical frequency analysis to phonocardiographic records the author could show that: 1. heart sounds are not composed of noises of short duration, as supposed hitherto, but consist of short complexes comprising a fundamental frequency and wholefigured upper partials; 2. the harmonic upper partials of first heart sound, second heart sound, and mitral opening snap have common zero-crossing points with the fundamental frequency, which means that there is phase balance between fundamental frequency and hormonics; 3. because of statements 1 and 2 one can conclude that spheric sound emitters are the sources of heart sounds; 4. a proposed vibration model is in aggreement with the statements 1 to 3. A vibration equation is derived from this model; 5. there is a strong correlation between the fundamental frequency of the first part of first heart sound and heart volume as well as between the fundamental frequency of mitral opening snap and volume of the left atrium; 6. variation in size of the left ventricle causes corresponding variations of the fundamental frequency of the first part of first heart sound; 7. in patients with mitral stenosis and atrial fibrillation it seems possible to evaluate the degree of stenosis by the variation of the fundamental frequency of the first heart sound; 8. the membranes of the heart valves are not the sources of heart sounds; 9. there was no evidence for the existence of a so called “pure muscle tone”.