What causes the disappearence of the systolic sound?
The absence of turbulence.
when pressure in the sphygmomanometer falls below systolic pressure, blood can again enter the artery. At first, blood enters only at peak systolic pressure, and the sound of blood pulsing through the artery becomes audible through the stethoscope. As the pressure falls further, the sound changes because the vessel is remaining open for longer periods. When the cuff pressure falls below diastolic pressure, blood flow becomes continuous, and the sound of the pulse becomes muffled…
its the sound of the diastolic and systolic movements. when the heart goes lubb, the heart is relaxing (diastolic movement) and dialating to let blood enter the heart chambers. The dubb sound is the sound of systolic movements, where the heart contracts and pushes blood out of the heart around the body.