How to Chart Lung Sounds With Accurate Terminology

Charting lung sounds accurately starts with using the right terminology, and the terminology itself has been a source of confusion for decades. A survey of pulmonary specialists and other physicians found that lung sound terms are not well standardized and that even the recommendations of the ATS/ACCP nomenclature subcommittee have not been widely adopted.¹ The consequence is that the same sound heard by two clinicians can end up charted with two different words, making the medical record unreliable. Getting charting right means knowing which terms carry a shared, defensible meaning and which ones invite misinterpretation.

Start With Normal Breath Sounds

Before you can document what is abnormal, your chart needs a baseline. Normal breath sounds fall into three recognized categories, and each belongs to a specific auscultation site. Vesicular sounds are the soft, low-pitched rustling heard over most of the peripheral lung fields. They are louder during inspiration and fade during expiration. Bronchovesicular sounds, heard near the upper sternum and between the scapulae, are moderate in pitch and roughly equal during both phases of breathing. Bronchial (or tracheal) sounds, heard directly over the trachea, are loud, high-pitched, and hollow, with expiration often louder than inspiration.

What sets these apart acoustically is how much the chest wall filters the sound. Vesicular breath sounds picked up over the chest wall show power that drops off steeply as frequency rises, while tracheal sounds carry a much broader frequency spectrum before sharply cutting off at higher frequencies.² When charting, document the type of breath sound and where you heard it. If vesicular sounds appear where you would expect bronchial sounds, or vice versa, that displacement itself is a finding worth noting, because it can signal consolidation, effusion, or other structural changes in the lung.

A common charting shortcut is writing “clear to auscultation bilaterally” or “CTA b/l.” This is acceptable when the exam truly is normal, but it becomes a problem when a clinician uses it reflexively without actually listening over all standard fields. If you did not listen to both anterior and posterior sites, do not chart that you did. Document the sites you assessed and the quality of breath sounds at each.

The Core Terminology Split You Need to Understand

Abnormal lung sounds are called adventitious sounds, and the single most important charting decision you make is whether the sound is continuous or discontinuous. Everything else flows from that distinction.

• Continuous sounds: last longer than about 250 milliseconds, have a musical or tonal quality, and include wheezes and rhonchi.
• Discontinuous sounds: are brief, nonmusical, explosive pops or clicks, and are called crackles.

This is where older terminology creates the most charting errors. The word “rales” has been used interchangeably with “crackles” for decades. In a nomenclature survey, pulmonary specialists used “crackles” and “rales” at roughly equal rates for discontinuous sounds, while physicians in other specialties preferred “rales.”¹ The ATS Ad Hoc Committee on Pulmonary Nomenclature recommended “crackles” as the standard term back in the 1970s, and most modern guidelines follow that recommendation. If you chart “rales,” you are not technically wrong, but you are using a term that many readers will find ambiguous. Worse, many authors have historically qualified “rales” with vague adjectives that do not convey a shared meaning.³ Chart “crackles” and specify whether they are fine or coarse.

How to Chart Crackles

Crackles are the short, popping sounds generated when collapsed or fluid-lined small airways snap open during inspiration or shut during expiration. Research on excised lungs has shown that crackles are produced by the opening of peripheral airways rather than by sudden inflation of alveoli.⁴ Expiratory crackles are caused by a similar but opposite process: sudden airway closure events that are far less energetic than the opening events heard on inspiration.⁵

When charting crackles, you need to document four things:

• Fine vs. coarse: Fine crackles are brief, high-pitched, and soft, often compared to the sound of hair rubbed between fingers near the ear. Coarse crackles are louder, lower-pitched, and longer in duration, sometimes compared to the sound of pulling apart Velcro.
• Phase: Are they inspiratory, expiratory, or both? Early inspiratory crackles tend to suggest obstructive disease, while late inspiratory crackles that start at the bases are more typical of restrictive processes like pulmonary fibrosis or heart failure.
• Location: Document the lung zone (upper, middle, lower) and laterality (right, left, bilateral). Bibasilar crackles tell a different clinical story than crackles isolated to a single upper lobe.
• Reproducibility: Do they clear with coughing? Crackles that disappear after a cough suggest mucus in larger airways. Crackles that persist through repeated breaths and do not clear are more concerning for parenchymal disease.

A well-charted crackle entry might read: “Fine, late-inspiratory crackles bilaterally at the bases, not clearing with cough.” Compare that to “rales heard in lungs,” which tells the next clinician almost nothing useful.

How to Chart Wheezes and Rhonchi

Wheezes are continuous, high-pitched, musical sounds produced when airway walls flutter in response to airflow through narrowed passages. The dominant theory holds that the sound arises from a combination of airflow-induced vibration of the airway walls and surrounding fluid.⁶ The proportion of the respiratory cycle occupied by wheezing correlates with the degree of bronchial obstruction better than pitch or loudness does, though the relationship is too scattered to reliably predict lung function from the sound alone.⁷

When charting wheezes, document whether they are monophonic (a single pitch, suggesting a single site of narrowing like a tumor or foreign body) or polyphonic (multiple pitches at once, typical of diffuse bronchoconstriction in asthma or COPD). Note whether they occur during inspiration, expiration, or both. Expiratory wheezes are far more common; inspiratory wheezes suggest more severe narrowing. Also note whether they are diffuse or localized to a specific region.

Rhonchi are the low-pitched continuous sounds, often described as snoring or gurgling, usually caused by secretions vibrating in larger airways. They have a frequency around 150 Hz and tend to be more prominent during expiration.⁸ Unlike crackles, rhonchi frequently change or disappear entirely after the patient coughs, because coughing clears the secretions responsible for the vibration.

Here is where charting gets tricky. The nomenclature survey found that the term “rhonchi” was frequently used to describe both continuous and discontinuous adventitious sounds.¹ That means when you write “rhonchi” in a chart, the next clinician may not know whether you heard a low-pitched continuous rumble or coarse crackles. Some experts have suggested abandoning “rhonchi” entirely and simply charting “low-pitched wheezes.” If you continue using the term, make sure you are describing a genuinely continuous, low-pitched, musical sound rather than a series of coarse crackles.

Stridor Deserves Its Own Entry

Stridor is a high-pitched sound resulting from turbulent airflow through a partially obstructed upper airway.⁹ Unlike wheezes, which originate in the lower airways, stridor is heard loudest over the neck and can often be heard without a stethoscope. It signals a potentially dangerous airway obstruction and should always be charted as an urgent finding.

When documenting stridor, note the phase of breathing. Inspiratory stridor typically points to obstruction at or above the glottis (vocal cords). Expiratory stridor suggests an obstruction below the glottis, in the intrathoracic trachea. Biphasic stridor, heard during both inspiration and expiration, indicates a fixed obstruction. Research on excised human larynxes has found that the frequency characteristics of stridor correlate more strongly with the degree of obstruction than with the specific anatomical site of the narrowing.¹⁰ In practical terms, this means you should not try to pinpoint the lesion based on pitch alone; chart what you hear and note whether it is inspiratory, expiratory, or biphasic.

Squawks and Other Uncommon Sounds

Squawks are short, musical inspiratory sounds that combine a crackle followed by a brief wheeze. They are relatively rare. In a large cohort of one thousand patients with interstitial lung disease, squawks were recorded in only about five percent of cases, and they were most commonly associated with hypersensitivity pneumonitis.¹¹ In patients with diffuse pulmonary fibrosis, squawks often occurred immediately after a loud crackle, suggesting that both sounds share an underlying mechanism: the sudden reopening of small airways, with the musical component arising from brief oscillation of the airway walls as they snap apart.¹²

If you hear a squawk, chart it as such. Do not try to shoehorn it into “wheeze” or “crackle,” because its clinical significance is different from either one in isolation. Squawks in patients with interstitial lung disease point toward fibrosing disease with bronchiolar involvement and were strongly associated with a mosaic pattern on high-resolution CT.¹¹

A pleural friction rub is another sound that deserves its own term. It is a grating, creaky sound heard during both inspiration and expiration, caused by inflamed pleural surfaces rubbing against each other. It can mimic coarse crackles, but it typically persists regardless of coughing and is localized to one area. Chart it by location and phase, and note that it does not clear with coughing, which helps the reader differentiate it from coarse crackles or rhonchi.

Why Interrater Reliability Is So Poor

Even when clinicians know the correct terms, they often disagree about what they are hearing. A study of pediatric respiratory auscultation found that only the identification of normal breath sounds reached even a moderate level of interrater reliability, with a kappa of 0.46. Agreement on abnormal sounds was much worse: stridor reached a kappa of 0.32, wheezes 0.25, and both crackles and rhonchi landed at just 0.15.¹³ A kappa of 0.15 is barely better than chance.

Several factors contribute to this problem. The human ear struggles to detect crackles when the background breath sound is loud; deep breaths mask more crackles than shallow ones. Fine crackles are easier to recognize because their waveform differs more sharply from the surrounding breath sound, while coarse crackles blend in.¹⁴ Ambient noise, stethoscope quality, patient body habitus, and how hard the patient is breathing all add variability.

What this means for charting is that precision in your documentation helps compensate for the inherent subjectivity. When you write “bilateral expiratory wheezes, polyphonic, diffuse, moderate intensity,” the next clinician gets a much clearer picture than “wheezing noted.” Even if two clinicians disagree on whether a particular sound is a fine crackle or a coarse crackle, the descriptive details you add around the term (timing, location, behavior with coughing) give the reader enough context to interpret your finding and compare it with their own exam.

Charting Lung Sounds in Infants and Children

Pediatric lung sounds differ from adult lung sounds in ways that affect how you interpret and chart them. Normal breath sounds in newborns contain higher-frequency components than those in adults, likely because the thinner, smaller pediatric chest wall does less acoustic filtering.¹⁵ Infant lung sound spectra also show less power in the low-frequency range below 300 Hz compared with older children and adults, which shifts the overall spectral profile upward.¹⁶

In practice, this means that what sounds like bronchovesicular or even bronchial breathing in an infant may actually be normal for that age, because the sound transmits so readily through the thin chest wall. Charting “bronchial breath sounds” in a three-month-old carries different clinical weight than the same entry in an adult, where it would strongly suggest consolidation. When charting pediatric exams, note the patient’s age explicitly and be cautious about applying adult-derived norms to what you hear. Terms like “transmitted upper airway sounds” are often more appropriate in neonates than “rhonchi,” because secretions in the nose and pharynx frequently produce a low-pitched rumble that transmits to the chest wall and can mimic lower airway pathology.

A Practical Charting Framework

Pulling all of this together, a reliable lung sound chart entry should include several consistent elements. Think of it as a checklist you run through for every finding:

• Breath sound type: Vesicular, bronchovesicular, bronchial, diminished, or absent.
• Adventitious sound name: Crackles (fine or coarse), wheezes (high-pitched), rhonchi (low-pitched continuous), stridor, squawk, or pleural friction rub.
• Timing: Inspiratory, expiratory, or biphasic. Early, mid, or late within the phase when relevant (especially for crackles).
• Location: Lung zone and side. Use anatomical landmarks or standardized zones (right upper lobe, left base, bilateral, diffuse).
• Quality modifiers: Monophonic vs. polyphonic for wheezes. Fine vs. coarse for crackles.
• Response to maneuvers: Clears with cough, worsens with deep breathing, absent in upright position, etc.

Some electronic health record systems offer dropdown menus that do not fully capture this level of detail. You may need to use the free-text field to add qualifiers. A dropdown that only allows you to select “wheezes” without specifying monophonic versus polyphonic, or “crackles” without noting fine versus coarse and the phase of respiration, produces a chart entry that is technically present but clinically incomplete. Whenever possible, supplement structured fields with free text that captures the features listed above.

Digital Stethoscopes and the Future of Documentation

Digital stethoscopes that record and store lung sounds are increasingly available, and deep learning algorithms are being developed to classify those recordings automatically. These systems typically convert lung sounds into visual spectrograms and then use neural networks to identify crackles, wheezes, rhonchi, and other patterns.¹⁷ The appeal is obvious: if a machine can classify the sound objectively and attach the recording to the chart, it sidesteps the interrater reliability problem entirely.

These tools are not yet standard in clinical workflows, but they are worth understanding because they will change how charting works. When a recording is attached to the chart, the terminology you use becomes less critical as the sole source of truth, since anyone can replay the sound. Even so, the written description still matters for rapid clinical communication. A physician scanning a chart at three in the morning is not going to play back audio files for every patient. The written note remains the first thing anyone reads, and using accurate, specific terminology in that note is the single best thing you can do to make the lung exam portion of your chart useful to others.