Lung auscultation follows a systematic side-to-side pattern using the diaphragm of your stethoscope, starting at the upper back and working downward while comparing the same level on each side. The technique is straightforward once you understand the landmarks, the sequence, and what you’re listening for. Here’s how to do it well.
Equipment and Setup
Use the diaphragm (flat side) of your stethoscope for lung sounds. Although some textbooks suggest using the bell, research supports the diaphragm as more appropriate for respiratory sounds because most breath sounds fall in the higher frequency range the diaphragm captures best.
Have the patient sit upright whenever possible. This is the best position for hearing clear lung sounds because it allows full expansion of the chest. If the patient can’t sit up, turn them side to side in a lying position to access both the anterior and posterior chest. Instruct the patient to breathe deeply through their mouth. Mouth breathing produces louder airflow sounds than nose breathing, making abnormalities easier to detect.
Ideally, place the stethoscope directly on bare skin. That said, one or two layers of light indoor clothing can be compensated for by pressing the stethoscope head more firmly against the chest. Under light pressure, fabric can muffle sounds by 5 to 18 decibels, but applying moderate to heavy pressure nearly eliminates that loss. Chest hair can create crackling artifacts that mimic abnormal sounds, so wetting the hair or pressing firmly can help reduce interference.
Where to Place the Stethoscope
Posterior Chest
The back is your primary listening surface because it gives you access to the largest area of lung tissue with the least obstruction from bone. Start at the top of the shoulders near the scapular line. Move down the back in a zigzag pattern, placing the stethoscope on one side, then crossing to the same level on the opposite side, then dropping down and repeating. Aim for four to eight spots on each side.
As you work your way down, keep the stethoscope close to the spine (the vertebral line) to avoid placing it over the scapula, where bone blocks sound transmission. Toward the bottom of the thorax, listen near the vertebral line and also move outward laterally to capture the lower lobes.
Lateral Chest
Ask the patient to raise their arms above their head or rest them on their head to open up the sides of the chest. On the right side, listen in three locations corresponding to the right upper, middle, and lower lobes. On the left side, listen in two locations for the left upper and lower lobes. The right lung has three lobes while the left has two, which is why the number of sites differs.
Anterior Chest
On the front of the chest, start just below the collarbones (the apices of the lungs sit here) and work downward in the same side-to-side comparison pattern. Listen in at least three to four spots on each side, moving from the upper chest down to the lower ribs. Avoid placing the stethoscope directly over the sternum (breastbone), and in female patients you may need to reposition breast tissue to access the lower anterior lung fields.
The Side-to-Side Comparison Pattern
The most important principle of lung auscultation is symmetry. You’re comparing the right lung to the left lung at the same level, every time. This is sometimes called the “ladder pattern”: listen on one side, cross to the mirror spot on the other side, drop down one level, and repeat. This approach lets you immediately notice if one side sounds different from the other, which is often the first clue that something is wrong.
At each spot, listen for at least one full breath cycle (one inhalation and one exhalation). Rushing through with partial breaths is one of the most common mistakes. Give yourself enough time to hear both phases clearly before moving on.
What Normal Breath Sounds Tell You
Healthy lungs produce three distinct types of breath sounds depending on where you listen. Knowing what’s normal at each location is what allows you to recognize when something is off.
Vesicular sounds are what you’ll hear over most of the lung fields, especially the posterior bases. They’re soft, low-pitched, and louder during inhalation than exhalation. This is the “normal” baseline sound of air moving through small airways and lung tissue.
Bronchial sounds are loud, harsh, and high-pitched, and they’re heard mainly during exhalation. You’ll normally hear these over the trachea (the windpipe) and sometimes at the right apex. If you hear bronchial sounds in areas where you’d expect vesicular sounds, that’s abnormal and suggests the lung tissue there has become denser, as happens with pneumonia.
Bronchovesicular sounds fall in between. They have a mid-range pitch, are audible during both inhalation and exhalation, and are commonly heard over the upper third of the anterior chest. These are normal in that location.
Recognizing Abnormal Sounds
Abnormal (adventitious) sounds layer on top of or replace normal breath sounds. Learning to identify them takes practice, but each has distinctive characteristics.
Crackles (also called rales) are short, popping, or explosive sounds, often compared to the sound of Velcro separating or rice cereal crackling in milk. They’re produced when collapsed small airways or fluid-filled air sacs snap open during inhalation. Crackles point toward conditions like pneumonia, pulmonary fibrosis, or fluid buildup in the lungs from heart failure. Fine crackles are softer and higher-pitched; coarse crackles are louder and lower.
Wheezes are high-pitched, musical sounds, usually heard during exhalation. They indicate narrowed airways and are strongly associated with asthma and COPD. Changes in wheezing patterns can signal the onset of an asthma attack or a COPD flare-up.
Rhonchi are low-pitched, musical sounds similar to snoring. They typically indicate secretions (mucus) in the larger airways and often clear or change character after the patient coughs.
Pleural friction rub is a grating, creaking sound heard during both inhalation and exhalation. It occurs when the normally smooth membranes lining the lungs and chest wall become inflamed and rub against each other.
Also pay attention to diminished or absent breath sounds on one side. This can indicate a collapsed lung, a large pleural effusion (fluid surrounding the lung), or severe air trapping in conditions like emphysema.
Voice Tests for Consolidation
If you suspect an area of the lung has become solid (consolidated), as in pneumonia, three voice tests can confirm it. All three work on the same principle: dense, fluid-filled, or collapsed lung tissue transmits sound more efficiently than normal air-filled tissue.
Egophony: Ask the patient to say “E” while you listen with the stethoscope. Over normal lung, you’ll hear “E.” Over consolidated tissue, the sound changes to a nasal “A,” often described as resembling the bleating of a goat. Egophony is also noted just above the level of a pleural effusion, where compressed lung tissue transmits higher-frequency sounds more efficiently.
Bronchophony: Ask the patient to say “ninety-nine” in a normal voice. Over healthy lung, the words sound muffled and indistinct. Over consolidated lung, the words come through abnormally loud and clear.
Whispered pectoriloquy: Ask the patient to whisper “one-two-three.” Over normal lung, you’ll barely hear anything. Over consolidated tissue, you’ll hear the whispered words clearly and distinctly. This test is particularly sensitive for detecting early or subtle consolidation.
Common Mistakes to Avoid
Listening through thick clothing without increasing pressure is one of the most frequent errors. If you can’t get to bare skin, press harder. Placing the stethoscope over the scapula on the posterior chest is another common mistake, since the bone blocks sound and makes breath sounds seem artificially diminished. Stay medial to the scapulae or move below them.
Not allowing enough time at each site leads to missed findings, especially subtle crackles that may only appear at end-inspiration. Have the patient take slow, deep breaths, and listen for a complete respiratory cycle before moving on. If you hear something questionable, stay and listen for several breaths to confirm whether the sound is consistent or was a one-time artifact from movement or chest hair.
Finally, always compare side to side rather than top to bottom. The natural variation in breath sounds from the apex to the base of the lung can mislead you if you’re listening sequentially down one side. Comparing the same level on both sides makes asymmetry obvious.