The phonocardiogram (PCG) detects and records heart sounds, the sounds made by the
various cardiac structures pulsing and moving blood. The sound is caused by the acceleration
and deceleration of blood and turbulence developed during rapid blood flow. The
essential technology for listening (“auscultation”) to heart sounds is still the basic stethoscope.
Electronic stethoscopes are available, but they have had little impact. Heart-sound
auscultation is both a science and an art. The science of the sounds that relate to a specific heart problem has been well established. The ability to discern the sounds or to recognize
the sounds that are being heard is perhaps the art, although time-frequency techniques
have been employed to analyze the phonocardiogram (Bulgrin et al., 1993).