Bookmark this page or print it for ward rounds · Updated 2026
Everything you need to identify heart and lung sounds in one place. Use this as a quick reference before exams, during clinical rotations, or whenever you need a refresher.
Heart sounds reference
Normal heart sounds
Sound
Timing
Mechanism
Key points
S1
Start of systole
Mitral + tricuspid valve closure
Louder at apex. Loud in short PR, mitral stenosis. Soft in MR, long PR.
S2
Start of diastole
Aortic + pulmonic valve closure
Louder at base. Physiologic split on inspiration is normal.
Extra heart sounds
Sound
Timing
Best heard
Significance
S3
Early diastole (after S2)
Apex, bell, left lateral
Normal in young adults. In >40 y/o: volume overload, heart failure.
S4
Late diastole (before S1)
Apex, bell, left lateral
Stiff ventricle: LVH, HOCM, acute MI. Absent in AFib.
Ejection click
Early systole (after S1)
Base
Bicuspid aortic valve, pulmonic stenosis.
Opening snap
Early diastole (after S2)
Apex / LLSB
Mitral stenosis. Closer to S2 = more severe.
Mid-systolic click
Mid-systole
Apex
Mitral valve prolapse. Earlier with standing, later with squatting.
Systolic murmurs
Murmur
Shape
Location
Radiation
Key feature
Aortic stenosis
Crescendo-decrescendo
RUSB
Carotids
Late-peaking = severe. Pulsus parvus et tardus.
Pulmonic stenosis
Crescendo-decrescendo
LUSB
Left shoulder
Ejection click that decreases with inspiration.
Mitral regurgitation
Pansystolic (uniform)
Apex
Axilla
Blowing quality. Louder with increased afterload.
Tricuspid regurgitation
Pansystolic
LLSB
-
Louder on inspiration (Carvallo's sign).
MVP
Late systolic
Apex
-
Preceded by mid-systolic click. Earlier with standing.
HOCM
Crescendo-decrescendo
LLSB
-
Louder with Valsalva and standing (decreased preload).
Flow murmur
Soft crescendo-decrescendo
LUSB
-
Grade ≤2, no thrill. Common in pregnancy, anemia, children.
Diastolic murmurs
Murmur
Shape
Location
Key feature
Aortic regurgitation
Decrescendo
LUSB / LLSB
Best heard sitting forward, end-expiration. Wide pulse pressure.
Mitral stenosis
Low-pitched rumble
Apex
Bell, left lateral decubitus. Opening snap. Pre-systolic accentuation.
Tricuspid stenosis
Low-pitched rumble
LLSB
Rare. Louder on inspiration.
Continuous murmurs & other sounds
Sound
Location
Key feature
PDA
Left infraclavicular
Machinery murmur, peaks at S2.
Venous hum
Right supraclavicular
Disappears lying down. Innocent in children.
Pericardial rub
LLSB
Scratchy, 3 components, positional. Sitting forward increases it.
Lung sounds reference
Normal breath sounds
Sound
Where heard
Character
Vesicular
Peripheral lung fields
Soft, low-pitched, inspiration > expiration. Normal finding.
Bronchial
Over trachea / manubrium
Loud, high-pitched, expiration ≥ inspiration. Abnormal if heard peripherally (consolidation).
Bronchovesicular
1st & 2nd ICS, interscapular
Intermediate. Inspiration = expiration.
Adventitious (abnormal) lung sounds
Sound
Character
Timing
Causes
Fine crackles
High-pitched, brief, "Velcro"
Late inspiratory
Pulmonary fibrosis, early CHF, atelectasis
Coarse crackles
Low-pitched, loud, bubbling
Early inspiratory
Bronchiectasis, pulmonary edema, pneumonia
Wheezes
High-pitched, musical, continuous
Expiratory (mostly)
Asthma, COPD, bronchospasm
Rhonchi
Low-pitched, snoring, continuous
Expiratory
Secretions in large airways. May clear with cough.
Stridor
High-pitched, harsh
Inspiratory
Upper airway obstruction: croup, epiglottitis, foreign body
Pleural rub
Creaking, leather-on-leather
Both phases
Pleurisy, PE, pleural infection
Quick-reference mnemonics
APT M — Auscultation order: Aortic, Pulmonic, Tricuspid, Mitral.
RILE — Right-sided murmurs louder on Inspiration; Left-sided louder on Expiration.
Ken-TUCK-y — S1-S2-S3 (S3 gallop rhythm).
TEN-nes-see — S4-S1-S2 (S4 gallop rhythm).
All diastolic murmurs are pathological. No exceptions.
Systolic murmurs ≤ grade 2 without other findings are often innocent — but always characterize fully.
From cheat sheet to recognition
A reference table tells you what to expect — but recognizing sounds in real time requires hearing them repeatedly. Auscultify turns this cheat sheet into active practice: 200+ real clinical recordings across six quiz modes that test whether you can identify each sound when you hear it. Ten minutes a day and the cheat sheet becomes unnecessary because the sounds live in your memory.
Auscultify