Abstract
(1) Phonocardiography is defined and the various bands of the vibratory spectrum are described, both from a physical standpoint and in relation to clinical methods of observation. Methods employed by various authors for recording phonocardiograms are compared. A new calibrated phonocardiograph is described. (2) International attempts at standardization of phonocardiography are summarized. Symbols for describing the vibrations of a phonocardiogram are discussed. (3) The advantages and disadvantages of various types of filters and the methods of calibrated and spectral phonocardiography are analyzed. (4) The vibrations created by the heart are separately described in the ultra-low, low, medium, and high frequency bands. A special discussion presents the author's viewpoints in regard to the two main components of the first sound and the so-called ejection sound. (5) The mechanism of production of the heart tones is described. (6) The value of the various tracings from a clinical standpoint is briefly analyzed.
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