Using a multi-filter system phonocardiograph and a dynamic microphone, 200 phonocardiograms of the normal Japanese were analysed.
(1) The systolic murmur was recorded in almost all normal subjects.
(2) The normal systolic murmur showed a graphic configuration of the ejection systolic murmur irrespective of the area of maximal intensity, and it was less in frequency and intensity than the pathological murmur.
a) The musical systolic murmur was observed in high incidence among young subjects, but not infrequently in adult life.
b) The non-musical pulmonic systolic murmur was the most freqeunt type of the normal systolic murmurs, except cases aged above 60.
c) The non-musical apical systolic murmur of aortic origin was frequently observed among elderly subjects.
d) The normal systolic murmur was rarely maximal in intensity at the aortic area.
(3) The above-mentioned phonocardiographic findings and their significances were discussed.