
Application to biomedical signals 221
4.5 Acoustic signals
4.5.1 Phonocardiogram
Phonocardiogram (PCG) is a recording of the acoustic signal produced by the me-
chanical action of the heart. The main frequency range of normal PCG is in the range
of 10-35 kHz; however in case of artificial heart valves frequencies up to 50 kHz may
be recorded. Heart sounds are generated by the vibration of the heart valves during
their opening and closure and by the vibration of the myocardium and the associated
structures. The sound generated by a human heart during a cardiac cycle consists of
two dominant components called first heart sound, S1, and the second heart