To listen to the heart with a stethoscope, you place the chest piece on specific spots on the chest, each corresponding to one of the heart’s four valves. Getting useful information from what you hear depends on three things: setting up the stethoscope correctly, knowing exactly where to place it, and understanding what normal and abnormal heart sounds actually sound like.
Setting Up the Stethoscope
Before the chest piece touches skin, the earpieces need to be pointing the right direction. Insert them so they angle forward, toward the bridge of your nose. This aligns the eartips with your ear canals, creating a seal that blocks outside noise and gives you a clear sound pathway. If you put them in backward, the tips rest against the outer ear cavity instead of sealing the canal, and you’ll hear almost nothing useful.
Most stethoscopes have two sides on the chest piece: a flat, wider diaphragm and a smaller, open bell. The diaphragm picks up higher-pitched sounds. The bell picks up lower-pitched sounds, particularly those below 200 Hz. Heart sounds span a wide range (roughly 20 to 650 Hz), so you’ll use both sides depending on what you’re listening for. On many modern stethoscopes, you switch between the two functions by adjusting how hard you press. Light pressure activates the bell mode, while firm pressure engages the diaphragm.
Where to Place the Chest Piece
There are five standard listening points on the chest. Each one is named for the heart valve you can hear best at that spot, not for the valve’s actual anatomical location. The sounds radiate along the path of blood flow, so the best listening spots are slightly removed from where the valves sit.
- Aortic area: Right side of the breastbone, in the space between the second and third ribs (2nd intercostal space).
- Pulmonic area: Left side of the breastbone, same rib level as the aortic area (2nd intercostal space).
- Erb’s point: Left side of the breastbone, one space lower, between the third and fourth ribs (3rd intercostal space). This is a good general listening spot where you can often hear sounds from multiple valves.
- Tricuspid area: Lower left edge of the breastbone, between the fourth and fifth ribs (4th intercostal space).
- Mitral area: The lowest and most leftward point. Between the fifth and sixth ribs on the left side, roughly in line with the middle of the collarbone (5th intercostal space, midclavicular line). This is the apex of the heart.
To find these spots, start by locating your collarbone. Just below it is the first rib, and the space beneath that rib is the first intercostal space. Count down from there. Work through all five points in order, spending several heartbeats at each one.
Getting a Clear Sound
Place the chest piece directly on bare skin. Clothing, even a thin shirt, creates friction noise that can mask heart sounds. Chest hair causes similar problems, producing crackling artifacts that mimic abnormal lung sounds. If chest hair is thick, pressing the chest piece more firmly can help, or you can lightly dampen the hair with water.
The room should be as quiet as possible. Heart sounds are inherently low in volume, and background noise competes directly. Have the person sit or lie still while you listen. Movement changes the air gap between the skin and the diaphragm, which degrades sound quality significantly.
What Normal Heart Sounds Sound Like
A healthy heart produces two distinct sounds per beat, often described as “lub-DUB.” These are called S1 and S2.
S1, the “lub,” happens when the mitral and tricuspid valves snap shut at the start of each heartbeat. The mitral valve contributes the louder portion. You’ll hear S1 most clearly at the mitral area (the lowest listening point on the left). S2, the “DUB,” is slightly higher in pitch and occurs when the aortic and pulmonic valves close after the heart finishes pumping. The aortic valve closes first and louder, because it works against higher pressure. S2 is heard best at the aortic area (upper right of the breastbone).
Between these two sounds, there should be silence. S1 marks the beginning of the heart’s contraction phase, and S2 marks the beginning of its relaxation phase. The gap between S1 and S2 is shorter than the gap between S2 and the next S1. This uneven rhythm is what gives the heartbeat its characteristic galloping quality even in a normal heart.
Recognizing Extra Heart Sounds
Sometimes you’ll hear a third or fourth sound in the cycle. These are called S3 and S4, and they fall in the very low frequency range, between 20 and 200 Hz. You need the bell side of the stethoscope to hear them, with light pressure at the mitral area.
S3 occurs just after S2, early in the relaxation phase. It sounds like a quick extra “thud” after the normal DUB, giving a rhythm sometimes described as “Ken-TUC-ky.” In children and young adults, S3 can be completely normal. In adults over 40, it often signals that the heart is struggling to pump effectively, as in heart failure, because it’s produced by blood rushing into a ventricle that’s overly stretched.
S4 occurs just before S1, right at the end of the relaxation phase. Its rhythm sounds like “TEN-nes-see.” S4 is produced when the heart’s upper chambers push blood into a ventricle that has become stiff, typically from long-standing high blood pressure or thickening of the heart muscle. S4 is almost always abnormal in adults.
Listening for Murmurs
Murmurs are whooshing or blowing sounds that fill the normally silent gaps between S1 and S2 (or between S2 and the next S1). They’re caused by turbulent blood flow, often from a valve that doesn’t open fully, doesn’t close completely, or a hole between heart chambers. Most heart sounds, including murmurs, fall below 300 Hz.
When you hear a murmur, pay attention to four things: where on the chest it’s loudest, when it occurs in the heartbeat cycle (between S1 and S2, or between S2 and S1), how loud it is, and whether it changes with position or breathing. Murmur loudness is graded on a 1 to 6 scale. Grade 1 is barely audible even in perfect conditions. Grade 2 is soft but clearly present. Grade 3 is easily heard but you can’t feel a vibration (called a thrill) on the chest wall. Grade 4 and above are loud enough to produce a palpable vibration, and a grade 6 murmur can actually be heard without a stethoscope at all.
How Body Position Changes What You Hear
Some heart sounds are easier to detect when the person shifts position. You can listen with the person lying flat on their back, sitting upright, or lying on their left side.
The left lateral decubitus position (lying on the left side) brings the apex of the heart closer to the chest wall. This makes low-pitched sounds at the mitral area louder. It’s particularly useful for hearing the rumbling murmur of mitral stenosis or an S3 sound. Place the bell lightly at the apex while the person lies in this position.
Having the person sit up and lean forward brings the base of the heart closer to the chest wall. This is the best position for hearing sounds related to the aortic valve and for detecting the friction rub of pericarditis (inflammation of the sac around the heart). Ask the person to exhale fully and hold their breath briefly while you listen at the upper right and left sternal borders with the diaphragm.
Breathing maneuvers also help. The Valsalva maneuver, where a person bears down as if straining, reduces the amount of blood returning to the heart. This makes most murmurs softer, but it makes the murmur of hypertrophic obstructive cardiomyopathy (a condition where thickened heart muscle blocks blood flow) noticeably louder. That contrast is one of the most reliable ways to distinguish this condition from a stiff aortic valve, which sounds similar at rest but gets quieter or stays the same during Valsalva.
Practicing Effectively
Heart auscultation is a skill that improves dramatically with repetition. Start by listening to as many healthy hearts as you can, so you develop a strong sense of what normal sounds like at each of the five points. Once the “lub-DUB” pattern is familiar, extra sounds and murmurs become much easier to notice. Listen at each point for at least five to ten heartbeats before moving on. Rushing through the sequence is the most common reason beginners miss subtle findings.
Many medical schools and online resources offer recordings of S3, S4, and common murmurs that you can compare against what you hear through the stethoscope. Training your ear with known examples before trying to identify sounds on a real person makes the learning curve significantly shorter.