The heart sounds are the heard in cardiac auscultation. Normally they are two ( 1st and 2nd ) separated by two silences ( large and small silent respectively ). Sometimes you can feel the existence of a third noise, and less frequently a fourth noise.In short, the heart sounds due to the closure of the valves on the inside of the ventricles or the beginning of the great arteries and which by its intensity are propagated to the walls of the thorax; There the ear captures them as noise.
