The two sounds have been described in words as "lubb dup" and their qualities indicate the state of the valves. Damage to the bicuspid or tricuspid valve effects the quality of the heart sound. When the semi-lunar valves are injured, a soft hissing noise "lubb shhh" is heard in place of the second sound. This is called heart murmur.

Heart murmur can occur as a result of any various heart valve defects, injured semi-lunar valves, or type of congenital heart disease, syphilis, and rheumatic fever. Research has shown that not all heart disease will cause murmurs and not all murmurs indicate heart disease.

In most case women that are pregnant will usually have heart murmurs that are caused by the normal increase in blood flow. There are also harmless heart murmurs that are common in infants and children cause by the rapid flow of blood through small structures in the heart. The vessel walls, valves and other tissues gradually will stiffen in the elderly sometimes causing turbulent blood flow even without any serious heart disease. A physician can tell by placing the stethoscope over arteries and veins elsewhere in the body and listening for sounds of turbulent blood flow. This type of blood flow is called bruits and is caused by narrowing of the vessels or abnormal connections between the vessels. Then the physician will feel the abdomen to determine if the liver is enlarged from a backup of blood in the major veins leading to the heart. He will also check the pulse and size of the abdominal aorta. If any abnormal abdominal swelling from fluid retention is present, this may indicate heart failure.