What Makes The Lub Dub Sound Jun 2026

The sound is created by the closing of the two atrioventricular (AV) valves: the mitral valve and the tricuspid valve. As the lower chambers of the heart (the ventricles) fill with blood and begin to contract, the pressure inside them spikes. This pressure forces the AV valves to snap shut, preventing blood from flowing backward into the upper chambers (the atria).

While we often say the valves "snap shut," the sound itself is actually caused by vibrations. When the valves close abruptly, they create turbulence in the blood and vibrations in the surrounding heart walls and major vessels. Think of it like a door slamming; the noise isn't just the wood hitting the frame, but the vibrations traveling through the wall and the air. Why These Sounds Matter what makes the lub dub sound

The lub-dub sound is produced by the closing of the heart's valves. There are two distinct sounds: The sound is created by the closing of

The "dub" is the sound of these exit valves snapping shut. It is a shorter, sharper, and higher-pitched sound than the "lub." It marks the moment the heart is empty and beginning to refill with blood for the next beat. While we often say the valves "snap shut,"

Every time you feel your pulse or press your ear to someone’s chest, you hear a rhythmic "lub-dub." This constant cadence is the soundtrack of life, but those sounds aren't actually the heart muscle squeezing. Instead, they are the sounds of your heart's valves snapping shut.