After the heart squeezes blood out to the lungs and body, the ventricles relax. The blood in the major arteries (the Aorta and Pulmonary Artery) wants to rush back into the heart, but two different valves—the Aortic and Pulmonary valves—snap shut to stop it. Their closure creates the "dub."
Thump-thump. Thump-thump.
A sharper, higher-pitched, shorter "dub." lub-dub sounds
It’s the most famous two-syllable sound on Earth. From the first time a doctor presses a stethoscope to a newborn’s chest, we are taught to listen for the “lub-dub.” But have you ever stopped to wonder what actually creates that iconic sound? Is it the heart beating? The blood moving? Or something else entirely?
Let’s pull back the curtain on the human body’s most important soundtrack. In simple terms, the "lub-dub" is the sound of your heart valves snapping shut. After the heart squeezes blood out to the
A slightly lower-pitched, longer "lub."
"The squeeze is starting. No blood is allowed back into the top rooms." Breaking Down the "Dub" (S2) The second sound, "Dub" (clinically known as S2 ), marks the end of systole and the beginning of rest (diastole). Thump-thump
Spoiler alert: It’s not the heart muscle contracting, and it’s not the blood whooshing around.
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