Which lung sound is most commonly associated with pneumonia?

• A. Rales
• B. Wheezing
• C. Rhonchi
• D. Stridor

Answer: (C)

Pneumonia most commonly presents with crackles (rales) on auscultation because the infection and inflammation fill the alveoli and small airways with fluid and debris, causing the small airways to snap open with inspiration and produce a crisp, crackling sound. This finding is the classic clue that air exchange in the distal lungs is being hindered by fluid-filled spaces.

Rhonchi are low-pitched sounds heard when secretions in larger airways create a rattling quality; they can appear with bronchitis or airway secretions but are not the most characteristic sign of pneumonia. Wheezing indicates narrowed or obstructed airways, as in asthma or COPD, not the typical infiltrative process of pneumonia. Stridor is a high-pitched, harsh sound from upper airway obstruction and is not associated with pneumonia.

So the best match for pneumonia is crackles due to alveolar involvement from infection and inflammation.