The noise you're hearing is the result of aortic stenosis; the narrowing of the aortic valve. Blood flow through the valve is ristricted which means the heart must contract harder in order to pump blood into the aorta. A common cause is age related calcification of the valve. If the valve is only mildly narrowed the patient is unlikely to have any symptoms, however, aortic stenosis can cause dizziness, chest pain, an irregular heart-beat and, in severe cases, heart failure.