Listening to heart sounds with a stethoscope requires placing the chest piece on five specific spots on the chest, using the right side of the stethoscope for each sound, and knowing what you’re hearing. The technique is straightforward once you understand where to listen, what normal sounds are, and how to set yourself up for the clearest audio possible.
The Five Listening Points on the Chest
Heart sounds are produced by valves snapping shut as blood moves through the heart’s chambers. Each of the four heart valves projects its sound to a slightly different spot on the chest wall. Cardiologists and nurses use five standard auscultation points, and the easiest way to find them is by counting the spaces between your ribs (intercostal spaces) starting just below your collarbone.
- Aortic area: Right side of the breastbone, in the space between the second and third ribs.
- Pulmonic area: Left side of the breastbone, at the same level (between the second and third ribs).
- Erb’s point: Left side of the breastbone, one space lower, between the third and fourth ribs.
- Tricuspid area: Lower left edge of the breastbone, between the fourth and fifth ribs.
- Mitral area: The apex of the heart, located between the fifth and sixth ribs on the left side, roughly in line with the middle of the collarbone.
A common approach is to move the stethoscope through these points in order, from the aortic area down to the mitral area. Spending at least a few heartbeat cycles at each spot gives you time to register what you’re hearing before moving on.
Bell Versus Diaphragm
Most stethoscopes have two sides on their chest piece: a flat, wider diaphragm and a smaller, concave bell. The diaphragm picks up higher-frequency sounds, while the bell captures lower-frequency ones. For general heart sounds (the normal “lub-dub”), the diaphragm works well. Switch to the bell when you want to hear low-pitched sounds, like certain extra heart sounds or specific murmurs at the mitral area.
Some modern stethoscopes combine both functions into a single surface. With these models, light pressure turns the chest piece into a bell, and firmer pressure against the skin shifts it toward diaphragm mode, making higher-frequency sounds louder and lower-frequency sounds quieter. If you’re using a combination chest piece, simply varying how hard you press gives you access to both frequency ranges without flipping sides.
What Normal Heart Sounds Are
The classic “lub-dub” you hear with every heartbeat consists of two distinct sounds, called S1 and S2. S1, the “lub,” happens when the mitral and tricuspid valves slam shut at the start of the heart’s pumping phase. The mitral valve closes slightly earlier and more loudly, so S1 is best heard at the mitral area near the apex. S2, the “dub,” occurs when the aortic and pulmonic valves close after the heart finishes pumping. The aortic valve closes first and louder because blood pressure in the aorta is higher than in the pulmonary artery. S2 is loudest at the aortic and pulmonic areas near the top of the breastbone.
The gap between S1 and S2 is systole, when the heart is actively squeezing blood out. The slightly longer gap between S2 and the next S1 is diastole, when the heart relaxes and refills. Recognizing which pause is shorter helps you orient yourself: the shorter silence sits between S1 and S2, the longer one between S2 and the next S1. You can also feel the pulse at the wrist simultaneously. The beat you feel lines up with S1.
Extra Heart Sounds
Beyond S1 and S2, you may sometimes hear a third sound (S3) or a fourth sound (S4). S3 occurs just after S2, during the early filling phase when blood rushes into the ventricle. In children and young adults, an S3 can be completely normal. In older adults, it often signals that the heart is struggling to handle its blood volume, as seen in heart failure. S4 happens just before S1 and represents the atria contracting forcefully against a stiff ventricle. It is almost always considered abnormal in adults. Both S3 and S4 are low-pitched sounds best heard with the bell of the stethoscope at the mitral area.
Hearing Murmurs
A murmur is a whooshing or swishing sound created by turbulent blood flow, often through a valve that is too narrow or doesn’t close completely. Murmurs are classified by when they occur in the heartbeat cycle. A systolic murmur falls between S1 and S2, during the heart’s pumping phase. A diastolic murmur falls between S2 and the next S1, during the filling phase. Diastolic murmurs are almost always abnormal, while some systolic murmurs are harmless, especially in children and young adults.
When evaluating a murmur, pay attention to several features: where on the chest it’s loudest, whether it occurs during systole or diastole, how long it lasts within the heartbeat, and whether it radiates (meaning you can follow the sound to a different location, like the neck or the armpit). These details help determine which valve is involved and how significant the problem might be.
Patient Positioning Makes a Difference
The position of the person you’re listening to can dramatically improve or muffle certain sounds. For the mitral area, having the person roll onto their left side (left lateral decubitus position) brings the apex of the heart closer to the chest wall. This makes S3, S4, and low-pitched mitral murmurs much easier to hear. In some cases, a loud S3 or S4 can even be felt as a subtle tap against your fingers in this position.
Having the person sit upright and lean forward brings the base of the heart closer to the chest wall, which is helpful for picking up murmurs from the aortic and pulmonic valves, particularly diastolic murmurs. Pericardial friction rubs, a scratchy sound caused by inflammation of the sac around the heart, are also best heard with the person leaning forward. Asking the person to exhale and briefly hold their breath reduces lung noise and can make faint heart sounds more audible.
Reducing Noise and Getting a Clean Sound
Small technique adjustments make a surprising difference in sound quality. Insert the earpieces so the tips angle forward, toward your nose. This follows the natural direction of your ear canals and creates a tighter seal that blocks ambient room noise.
Hold the chest piece between the middle segments of your index and middle fingers, with your thumb tucked underneath the tubing. This grip prevents the tubing from brushing against the person’s skin or clothing, which creates scratching artifacts that sound alarmingly like cardiac abnormalities but are just noise. Keep your remaining fingers slightly lifted so they don’t accidentally drag across the skin either.
A quiet room matters more than you might expect. Turn off televisions, fans, or anything generating background hum. If the person has significant chest hair, pressing the chest piece more firmly can help maintain skin contact, though wetting the hair slightly also works. Place the stethoscope directly on bare skin whenever possible, since listening through clothing adds layers of friction noise and muffles the sounds you’re trying to hear.
Listening to Children
Auscultation in children follows the same five-point approach, but a few things change. Children have thinner chest walls, so heart sounds are naturally louder and closer together. A child’s resting heart rate is significantly faster than an adult’s, which compresses the gaps between S1 and S2 and makes it harder to tell systole from diastole. Feeling the pulse simultaneously is especially helpful here.
Infants and toddlers add the challenge of movement and crying. A crying baby tenses the chest muscles and generates noise that drowns out heart sounds. Feeding, using a pacifier, or simply waiting for a calm moment often works better than trying to listen through the noise. A smaller pediatric chest piece provides better skin contact on a small chest, improving sound quality compared to an adult-sized diaphragm.
Digital Versus Acoustic Stethoscopes
Electronic stethoscopes can filter background noise, amplify heart sounds, and in some cases record audio for later review. A study comparing electronic and traditional acoustic stethoscopes in obese patients (where extra tissue makes auscultation harder) found that the electronic stethoscope detected cardiac abnormalities with noticeably higher sensitivity: 60.1% versus 45.7% for acoustic models when combining results across different valves and experience levels. Specificity, meaning the ability to correctly rule out a problem that isn’t there, was essentially the same between both types at around 93 to 94%.
For most people learning to listen to heart sounds, a quality acoustic stethoscope is perfectly adequate. Electronic models offer an advantage in challenging situations like obesity, noisy environments, or when you need to share a recording with someone else. Some digital stethoscopes also offer visual waveform displays that let you see the sound pattern while you listen, which can be a useful learning tool when you’re still training your ear to distinguish S1 from S2 or pick out a faint murmur.