Which heart sounds are considered normal?

The sounds considered normal in cardiac auscultation are S1 and S2. S1 corresponds to the closure of the mitral and tricuspid valves at the beginning of systole, while S2 is associated with the closure of the aortic and pulmonary valves at the end of systole. These two sounds are essential indicators of proper heart function and are typically heard during a routine examination.

S3, often referred to as a "physiological third heart sound," can be normal under certain conditions, particularly in children and young adults, but in older adults, it may suggest heart failure or volume overload. S4, which is associated with atrial contraction and is often linked to conditions such as hypertension or stiffened ventricles, is typically not considered a normal sound in a healthy individual. Therefore, while S3 can be seen in some populations, it is not universally regarded as a normal finding across all age groups, making S1 and S2 the standard "normal" heart sounds. This focus on S1 and S2 is what makes this answer accurate in the context of defining normal heart sounds.