Why is the muffling of the sound said to indicate the diastolic pressure?

The muffling of sound during blood pressure measurement corresponds to the diastolic pressure because it occurs when the blood flow resumes through the artery after the pressure in the cuff is released. Initially, as the cuff pressure decreases, the sounds of turbulent blood flow (Korotkoff sounds) are heard. When these sounds begin to soften and eventually disappear, it indicates that the arterial pressure has fallen to the level of diastolic pressure, where the heart is at rest between beats. Thus, the transition from distinct sounds to muffled sounds marks the point of diastolic pressure.