Nursing care
Breath Sounds: the method, the errors, and the exam
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated September 2026
Short answer
Breath sound assessment uses a stethoscope moved systematically over the chest to detect airway narrowing, fluid and secretions. The key bedside distinction is that crackles do not clear with a cough, because they come from fluid or collapsed alveoli, while rhonchi do clear, because they come from secretions in the larger airways that a cough can mobilise.
What the skill is for
Auscultating breath sounds lets a nurse localise a respiratory problem to the airway, the alveoli or the pleura without waiting for imaging. Different adventitious sounds point to different pathology: wheezes to bronchoconstriction, crackles to fluid or alveolar collapse, rhonchi to secretions in larger airways, and a pleural friction rub to inflamed pleural surfaces rubbing together.
This is a repeated assessment, not a one-off check. Comparing today's findings against yesterday's tells you whether a patient with heart failure is accumulating fluid, whether a post-operative patient is retaining secretions, or whether a bronchodilator has actually worked. The single most useful bedside distinction, and the one that decides the intervention, is whether an adventitious sound clears when the patient coughs.
The method, step by step
Ask the patient to sit upright if possible, breathe through the mouth slightly deeper than normal, and expose the chest so the stethoscope diaphragm sits on skin, not clothing. Warm the diaphragm in your hand first if it is cold, since a startled shallow breath from a cold stethoscope ruins the assessment.
Move systematically, comparing side to side rather than working straight down one lung: apex to base, anterior then posterior, listening to at least one full inspiration and expiration at each point before moving on. Note the sound's location, timing within the respiratory cycle, and whether it changes with a deep breath or a cough. Document using standard terminology, not vague descriptors, so the next nurse can compare directly against your findings.
Where it goes wrong
The most common technical error is listening through clothing or a gown, which muffles or fabricates crackle-like sounds that aren't real. Listening for only a breath or two at each site, rather than a full inspiratory-expiratory cycle, means transient sounds get missed entirely.
The more consequential error is interpretive: treating crackles and rhonchi as interchangeable 'crackly noises' rather than distinct findings with different causes. Crackles do not clear with a cough, because they arise from fluid in the alveoli or small airways popping open, as in pulmonary oedema or pneumonia. Rhonchi do clear with a cough, because they arise from mucus vibrating in larger airways that a strong cough can physically shift. Confusing the two leads to the wrong intervention: pushing fluids and encouraging deep coughing does nothing for crackles caused by fluid overload, and may worsen it.
Practising it deliberately
Practise the auscultation sequence until the side-to-side, apex-to-base pattern is automatic, and time yourself listening a full respiratory cycle at each site rather than rushing. Use recorded lung sound libraries to drill the difference between fine crackles, coarse crackles, rhonchi and wheeze until you can name a sound within a few seconds of hearing it.
Build the cough test into your practice explicitly: after identifying an adventitious sound, mentally rehearse asking the patient to cough and re-auscultating. Say out loud what each outcome would mean, fluid if it persists, secretions if it clears, so the clinical reasoning becomes as automatic as the sound recognition itself.
Applying it on the exam
NCLEX questions on breath sounds usually describe a finding and expect you to name the underlying process or the correct intervention, not just the sound's label. A question describing crackles that persist after coughing, in a patient with jugular venous distension and pedal oedema, is pointing at fluid overload and heart failure, with diuretics and fluid restriction as the relevant interventions, not chest physiotherapy.
A question describing rhonchi that clear after a productive cough, in a post-operative or immobile patient, is pointing at retained secretions, with deep breathing, coughing, incentive spirometry and suctioning as the relevant interventions. The exam relies on you knowing which finding responds to which intervention category, so memorising the sound names alone without the cough-response distinction will not get you to the right answer.
A worked example
A patient three days post-abdominal surgery has bilateral coarse crackles at the lung bases and a weak, guarded cough due to incisional pain. You ask the patient to cough deeply and re-auscultate: the sound clears in the right base but persists faintly in the left.
The clearing on the right confirms retained secretions there, responsive to incentive spirometry, splinted coughing and adequate analgesia to allow a deeper effort. The persistence on the left needs a second look rather than the same secretion-focused plan, since fluid that doesn't clear with a cough is not managed by encouraging more coughing. Reassessing after the intervention, not assuming it worked, is what the finding calls for.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our respiratory practice questions are the closest set to what this page covers.
Common questions
How do you tell crackles from rhonchi at the bedside?
Ask the patient to cough, then re-auscultate the same site. Crackles persist because they come from fluid or collapsed alveoli, which a cough can't clear. Rhonchi disappear or change because they come from secretions in larger airways, which a cough can mobilise.
What does a wheeze on expiration usually indicate?
Expiratory wheeze usually points to narrowed lower airways, as seen in asthma or bronchospasm. If it's heard on both inspiration and expiration, it suggests more significant obstruction and warrants prompt reassessment.
Why do you listen for a full respiratory cycle at each site?
Some adventitious sounds, particularly fine crackles late in inspiration, only appear briefly. Cutting the assessment short at each site risks missing findings that only show up at a specific point in the breath.
Is a pleural friction rub the same as crackles?
No. A friction rub has a dry, grating quality heard on both inspiration and expiration and comes from inflamed pleural surfaces, not fluid or secretions in the airway itself. It typically doesn't change with coughing either.