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What are heart sounds and how to know if they’re normal

Medically reviewed by Jeffrey S. Lander, MD Key Takeaways S1 and S2 are the normal heart sounds you hear when the heart ...
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What to Know About the Third (S3) Heart Sound

A third heart sound, or S3, is a low-frequency, extra heart sound that may be heard with a stethoscope right after the normal S1 and S2 heart sounds. S1 and S2 are the "lub-dub" sounds of a heartbeat ...