Heart sounds are best heard at five specific spots on the chest, each corresponding to a different heart valve. These listening points don’t sit directly over the valves themselves. Instead, they follow the direction blood flows after passing through each valve, which carries the sound to a nearby area on the chest wall where it’s loudest and clearest.
Why the Listening Points Don’t Match the Valve Locations
This is the detail that surprises most people. The aortic valve, for example, sits behind the breastbone at the level of the third rib space, but its sound is best heard one space higher and to the right. The mitral (bicuspid) valve projects to the left of the fourth rib space, yet you hear it best at the fifth rib space further out toward the left side of the chest. Each valve’s sound travels downstream with the blood, landing on the chest wall at a slightly different location than the valve’s true anatomical position. All the valves also shift slightly lower when a person is standing compared to lying down.
The Five Auscultation Points
Clinicians use five standard points, often remembered by moving in a rough pattern from the upper right chest down and to the left. Here’s where each one sits:
- Aortic area: Right side of the breastbone, second rib space (the gap between the second and third ribs). This is where the sound of the aortic valve closing is loudest.
- Pulmonic area: Left side of the breastbone, second rib space. This mirrors the aortic point on the opposite side and captures the pulmonic valve.
- Erb’s point: Left side of the breastbone, third rib space. This is a transition zone where the second heart sound is especially clear. It’s also a useful spot for picking up murmurs from aortic valve problems.
- Tricuspid area: Lower left edge of the breastbone, fourth rib space. The tricuspid valve sound is best detected here.
- Mitral area (the apex): Fifth rib space on the left side, roughly in line with the middle of the collarbone. This is the lowest and most outward point of the five, sitting right over the tip of the heart.
For female patients, breast tissue can sit over the mitral area. Lifting the breast so the stethoscope rests directly on the chest wall makes a significant difference in sound quality.
What You’re Actually Hearing
The two normal heart sounds, commonly written as “lub-dub,” come from valves snapping shut at different moments in the heartbeat cycle.
The first sound (S1) happens when the mitral and tricuspid valves close at the start of the heart’s pumping phase. It marks the beginning of systole, when the ventricles contract and push blood out. S1 is loudest at the mitral and tricuspid areas near the bottom of the breastbone.
The second sound (S2) occurs when the aortic and pulmonic valves close at the end of that contraction. Blood in the aorta and pulmonary artery briefly reverses direction, hits the closed valve leaflets, and the sudden deceleration of that blood column sets the valve cusps, vessel walls, and surrounding structures vibrating. Those vibrations are what you hear. S2 is loudest at the aortic and pulmonic areas near the top of the breastbone, and it’s particularly clear at Erb’s point.
Extra Heart Sounds: S3 and S4
Beyond the normal two sounds, some people have a third or fourth heart sound. These are low-pitched and quiet, easy to miss if you’re not listening with the right technique.
S3 is a soft sound that occurs just after S2, during the early filling phase when blood rushes into the ventricles. In young, healthy people and during pregnancy, an S3 can be completely normal. In older adults, it often signals that the heart is struggling to pump effectively, particularly in heart failure.
S4 arrives just before S1, produced when the atria contract forcefully against a stiff or thickened ventricle. It’s rarely considered normal and typically points to conditions where the heart muscle has become less compliant, such as long-standing high blood pressure or thickening of the heart wall. Both S3 and S4 are heard best at the apex (mitral area), especially with the patient rolled onto their left side.
How Body Position Changes What You Hear
Certain sounds only become audible when the patient shifts position, because gravity changes how blood moves through the heart and which structures press closer to the chest wall.
Lying flat on the back (supine) is the standard starting position and works well for most sounds. Rolling onto the left side, called the left lateral decubitus position, brings the apex of the heart closer to the chest wall. This is the best position for hearing mitral valve sounds, especially the low-frequency rumble of mitral stenosis and the faint S3 or S4.
Sitting up and leaning forward pushes the base of the heart closer to the front of the chest. This position makes aortic valve murmurs easier to detect, particularly the soft, blowing sound of a leaky aortic valve. In rare cases, pericardial sounds (from inflammation of the sac around the heart) are best heard with the patient on hands and knees.
Stethoscope Technique Matters
A stethoscope has two sides for a reason. The flat diaphragm picks up higher-pitched sounds: normal S1 and S2, most murmurs, and clicking sounds. The bell, the smaller concave side, is designed for low-pitched sounds like S3 and S4. Pressing the bell firmly against the skin actually stretches the skin into a makeshift diaphragm, filtering out the low frequencies you’re trying to hear. Light contact is key when using the bell.
Where Murmurs Radiate
Murmurs don’t always stay put at a single point. The direction a murmur spreads across the chest, called its radiation pattern, is one of the most useful clues for identifying which valve is involved.
Aortic stenosis, a narrowing of the aortic valve, produces a harsh sound at the right upper chest that often radiates up into the neck along the carotid arteries. You can sometimes hear it or even feel a vibration (called a thrill) by placing fingers on the side of the neck.
Mitral regurgitation, a leaky mitral valve, generates a murmur loudest at the apex that radiates toward the left armpit. This leftward spread is distinctive and helps separate it from aortic problems, which travel upward instead.
A Systematic Listening Sequence
Rather than jumping between points randomly, clinicians typically follow a set path to avoid missing anything. One common approach starts at the apex with the patient rolled onto their left side, then moves to the lower left sternal border with the patient flat on their back. From there, the stethoscope walks upward along the left side of the breastbone, one rib space at a time, then crosses to the right upper chest and moves back down. The examiner also checks the left armpit for radiating mitral murmurs and the area above the collarbones for sounds transmitted from the great vessels.
This sequence ensures every valve area gets assessed with both the diaphragm and the bell, in multiple positions. The whole process takes only a few minutes but covers an enormous amount of diagnostic ground.