Where to Place a Stethoscope for Heart and Lung Sounds

Heart sounds are best heard at five specific spots on the front of the chest, each aligned with the flow path of a particular heart valve, while lung sounds require a systematic survey of at least six points on the back of the chest, moving from the upper lung fields down to the bases. Placement matters because even a centimeter or two of drift can make the difference between catching a subtle murmur or crackle and missing it entirely. The landmarks themselves are straightforward once you learn to count rib spaces, but there are enough practical wrinkles that placement in the real world rarely goes as neatly as the textbook diagrams suggest.

The Five Classic Spots for Heart Sounds

Cardiac auscultation revolves around five named locations on the anterior chest. Each one sits where blood flowing through a specific valve projects its sound most clearly to the chest wall. The points are named after the valves, but they do not sit directly over the valves themselves. Instead, they follow the direction blood travels after passing through each valve.¹

• Aortic area: right side of the breastbone (sternum) at the second intercostal space, which is the gap between the second and third ribs. This is where the aortic valve’s closure sound comes through most clearly.
• Pulmonic area: left side of the sternum, also at the second intercostal space, mirroring the aortic spot on the opposite side. This highlights the pulmonic valve.
• Erb’s point: left side of the sternum at the third intercostal space, roughly halfway between the pulmonic and tricuspid areas. It is a useful listening post for the second heart sound and for picking up aortic regurgitation murmurs.
• Tricuspid area: lower left sternal border at the fourth intercostal space, between the fourth and fifth ribs.
• Mitral area: the apex of the heart, found at the fifth intercostal space on the left side, along the midclavicular line (an imaginary vertical line dropped from the middle of the collarbone). This is the lowest and most lateral of the five spots.

In practice, most clinicians work through these five points in order, either top to bottom or bottom to top, listening at each for a few cardiac cycles before moving on. The goal is to compare what you hear at each location. A murmur that is loudest at the apex and fades as you move toward the base of the heart suggests mitral valve involvement, while a murmur that peaks at the right upper sternal border points toward the aortic valve. Techniques like having the patient lean forward, lie on the left side, or perform a Valsalva maneuver can change how loud a murmur is and help narrow down its source, though no single maneuver is perfectly reliable on its own.²

Where to Listen for Lung Sounds

Lung auscultation uses a different map. The posterior chest, meaning the patient’s back, is the primary listening surface because the lungs extend much farther back than most people realize, and the back gives you access to both upper and lower lobes without the heart or sternum getting in the way. A standard approach involves at least six posterior sites: two high up near the tops of the shoulders (upper lobes), two in the middle of the back at roughly the level of the shoulder blades (middle fields), and two at the bases below the shoulder blades (lower lobes). You listen on both left and right sides at each level and compare them, because asymmetry between the two lungs is often the most telling finding.

The lower lobes tend to be the most clinically productive real estate. A study examining auscultation sites in clinical practice found that the lower lobe fields on the posterior thorax were the most common locations where abnormal sounds were recorded.³ That makes sense: fluid, mucus, and early pneumonia consolidation tend to collect in the dependent (lowest) parts of the lungs, especially in patients who have been lying down.

You can also listen on the anterior chest and the lateral chest walls, particularly when a patient cannot sit up. Anterior listening adds the area just below each collarbone (for the upper lobes) and the lower anterior chest at the mid-axillary line (for the lower lobes). The lateral approach, listening under the armpits, is helpful for catching sounds in the lingula on the left side and the right middle lobe, two areas that are partially hidden on both the front and back.

What Normal Sounds Tell You About Placement

Understanding what a normal breath sound should sound like at a given spot is essential, because it is the departure from normal that alerts you to trouble. Over most of the peripheral lung fields, you hear vesicular breath sounds: soft, low-pitched, and rustling, with a longer inspiratory phase and a shorter, quieter expiratory phase. These sounds are generated locally within the lung tissue itself, probably at the level of the small airways deep inside each lobe.⁴

Over the trachea and main bronchi (listened to at the neck or the upper sternum), you hear bronchial or tracheobronchial sounds: louder, higher-pitched, and tubular, with the expiratory phase roughly equal to or longer than inspiration. These are produced by turbulent airflow in the upper airways. If you hear bronchial-type sounds out in the peripheral lung fields where vesicular sounds should be, that is a red flag for consolidation. Consolidated lung tissue, such as in pneumonia, conducts the high-frequency sounds from the central airways out to the chest wall more efficiently than normal aerated lung does.⁴ In other words, the same stethoscope position can sound completely different depending on what the underlying lung tissue is doing.

Bell Versus Diaphragm

Most modern stethoscopes are dual-headed, with a flat diaphragm on one side and a smaller concave bell on the other. The diaphragm is pressed firmly against the skin and filters out low-frequency sounds, making it better for picking up high-pitched findings like the second heart sound, aortic regurgitation murmurs, and most lung sounds. The bell, held lightly against the skin, lets low-frequency sounds through and is the tool of choice for low-pitched heart sounds like the third heart sound (S3), the fourth heart sound (S4), and the rumble of mitral stenosis.

Research comparing the two sides confirms that the diaphragm responds better to higher-frequency sound components.⁵ The practical takeaway: use the diaphragm for most of your cardiac and all of your lung listening, then switch to the bell at the mitral and tricuspid areas when you specifically want to hunt for low-frequency gallops or rumbles. One common mistake is pressing the bell too firmly against the skin, which stretches the skin into a makeshift diaphragm and defeats the purpose.

Placement in Children Under Two

Pediatric patients, especially infants and toddlers, present a different challenge. Their chests are small, their hearts and lungs overlap more, and the five adult cardiac landmarks are compressed into a much tighter space. A study looking at optimal precordial stethoscope placement in children younger than two tested three sites and found meaningful tradeoffs. The site that scored highest for lung sounds (placed more laterally) scored poorly for heart sounds, and the site that performed best for heart sounds (placed more centrally over the precordium) was mediocre for lungs. A third site scored well for lung sounds but poorly for heart sounds.⁶

This means there is no single “best” spot on a small child’s chest for hearing both heart and lung sounds simultaneously. If you need to monitor both during anesthesia or a procedure, you may need to reposition the stethoscope or use two separate monitoring points. For routine examination, the approach is similar to adults, just scaled down: listen over the precordium for the heart, and listen on the back for the lungs, recognizing that sounds from one organ will inevitably bleed into the other given how close everything is.

Common Mistakes That Degrade Sound Quality

Even with perfect placement, several practical errors can ruin what you hear. Listening through clothing is the most common. It is tempting, especially in busy clinical settings, to skip the step of exposing the patient’s chest. Some research suggests that thin, single-layer fabric does not drastically attenuate all lung sounds, but auscultation through clothing remains problematic because it introduces friction artifacts (rustling sounds that mimic crackles) and prevents the examiner from inspecting or percussing the chest at the same time.⁷ The safest practice is direct skin contact whenever possible.

Other common pitfalls include listening in a noisy room, failing to ask the patient to breathe deeply through an open mouth (shallow nasal breathing generates very faint lung sounds), and placing the stethoscope over bone rather than in the intercostal spaces. The ribs themselves are poor sound conductors. If you find yourself struggling to hear anything at a cardiac landmark, you may simply be sitting on a rib rather than in the space between two ribs. Repositioning by even half a centimeter can make a surprising difference.

How Accurate Is Auscultation in Practice

Despite being the oldest and most widely used bedside exam tool, auscultation has real limitations in diagnostic accuracy, and understanding those limitations is part of knowing when placement alone is not enough. A meta-analysis covering 34 studies found that the overall pooled sensitivity of lung auscultation for detecting acute pulmonary problems was only about 37%, though specificity was much higher at roughly 89%.⁸ In plain terms, auscultation is good at confirming a problem when it hears something abnormal, but it frequently misses abnormalities that are actually present.

A study in critically ill patients comparing auscultation with lung ultrasound reported similar numbers: the overall diagnostic accuracy of auscultation was about 67%, with sensitivity for detecting crackles around 66% and sensitivity for rhonchi (coarse, continuous sounds) at 47%.⁹ In heart failure patients specifically, auscultation caught pulmonary congestion with only about 53% sensitivity, while its specificity was high at roughly 96%.¹⁰

None of this means auscultation is useless. A highly specific test still has value: if you hear crackles at the lung bases, there is a strong chance something is genuinely wrong there. But a clear-sounding chest does not reliably rule out disease, particularly in obese patients, in noisy environments like emergency departments, or in the early stages of fluid accumulation. This is why clinicians increasingly pair the stethoscope with point-of-care ultrasound for higher-stakes decisions.

Remote and Telemedicine Auscultation

The rise of telehealth raised an obvious question: can you auscultate remotely? The answer is a qualified yes. Validation studies using electronic stethoscopes paired with video links have shown that remote heart and lung exams can agree with traditional bedside auscultation in about 92% of patients. When broken down by organ, heart auscultation items matched at roughly 96%, while lung items agreed at about 84%.¹¹

The catch is that someone still has to place the stethoscope on the patient’s body, whether that is a nurse, a family member, or the patient themselves. Getting untrained people to find the right intercostal spaces is the bottleneck. Heart auscultation, with its five discrete landmarks, translates to remote guidance more easily than lung auscultation, which requires systematic movement across the entire posterior chest. The lower agreement rate for lung sounds likely reflects the difficulty of guiding someone to cover all the necessary sites without skipping areas or introducing artifact from movement.

Keeping the Stethoscope Clean

Stethoscope hygiene is an underappreciated part of the auscultation process that most training glosses over. The diaphragm and bell make direct contact with skin at every patient encounter, and contamination rates are consistently high. A study across three hospitals found bacterial colony counts ranging from about 27 to 51 colony-forming units per square centimeter on stethoscope surfaces. Staphylococcus species contaminated roughly 37% of the stethoscopes tested, with methicillin-resistant Staphylococcus aureus (MRSA) found on about 17% and vancomycin-resistant strains on nearly 2%. Over a third of isolates were resistant to two or more antibiotics.¹²

The fix is simple in principle: wipe the diaphragm and bell with an alcohol pad between every patient. In practice, compliance is low, especially during busy shifts. Some institutions have moved to disposable stethoscope covers or patient-dedicated devices in isolation rooms, but the most practical habit remains a quick alcohol wipe before and after each use. Given that you are pressing the same surface against multiple patients’ bare skin in exactly the areas where pathogens colonize, this is one of the easiest infection-control wins available.

How the Stethoscope Got Its Landmarks

The auscultation points used today trace back surprisingly directly to one person. In 1816, French physician René Laënnec rolled a sheet of paper into a tube to listen to a patient’s chest, finding that the improvised cylinder transmitted heart and lung sounds more clearly than pressing his ear directly against the patient. He went on to develop the first dedicated stethoscope, systematically cataloged the sounds of various heart and lung diseases, and confirmed his diagnoses against autopsy findings.¹³ His 1819 treatise, “De L’auscultation Médiate,” was essentially the first manual on where and how to listen. The five cardiac landmarks and the systematic approach to posterior lung fields that clinicians learn today are refinements of the framework Laënnec established over two centuries ago. The stethoscope’s design has evolved from a wooden monaural tube to a binaural instrument with tunable diaphragms, but the underlying logic of placement has changed remarkably little.