One of the oldest diagnostic tools is the stethoscope, which is used to hear sounds inside the body clearly and distinctly. It is usually made of two long rubber tubes (one for each ear) that are attached to a metal bell containing a thin plastic diaphragm. When the bell is placed on the chest, the diaphragm vibrates and amplifies the sounds. The stethoscope allows the doctor to hear the sounds of the heart as it contracts and relaxes as well as sounds produced by the lungs and blood vessels. Each sound provides important clues as to how well your heart, lungs and blood vessels are functioning.

The sounds of the heart are usually referred to as a continuous "lub dubÉ lub dubÉlub dub," the first and second heart sounds. The "lub" is the sound made by the contraction of the ventricles and the closing of the mitral and tricuspid valves. The "dub" is related to the closing of the aortic and pulmonary valves. Additional sounds such as clicks, rubs, murmurs and snaps usually, but not always, suggest an abnormality and may require further analysis by special procedures. For example, if youÕre over the age of 30 and your doctor hears a third low pitched sound after the dub, it may signal heart failure. Valves that donÕt close completely make blowing noises called murmurs.