What Is Lub Dub: Sound

The order is based on the in the heart cycle. Systole (contraction) always comes before diastole (relaxation). The AV valves (lub) must close at the start of contraction. The semilunar valves (dub) close at the end of contraction.

But what exactly causes these two distinct sounds? Why doesn't the heart make just one sound? And what happens when "lub-dub" turns into something else, like a "whoosh" or a "click"? what is lub dub sound

If you’ve ever listened to a healthy heart through a stethoscope, the sound you hear is a familiar, two-beat rhythm: lub-dub, lub-dub, lub-dub . This is not just a random noise; it is the acoustic signature of your heart valves snapping shut. It is the sound of life itself. The order is based on the in the heart cycle