Stethoscope Function: Listening to Heart Sounds, Not Measuring Rate

A stethoscope is an acoustic listening device. It amplifies internal body sounds—heart valves closing (S1, S2), murmurs, lung sounds, bowel sounds, bruits. It does not measure heart rate numerically.

Heart Rate Measurement

• Manual: Palpate radial/carotid pulse; count beats for 30–60 seconds.
• Pulse oximeter: Photoplethysmography at fingertip.
• ECG monitor: Electrical activity (gold standard).
• Smartwatch/fitness tracker: Optical heart rate (PPG).

Clinical Use of Stethoscope

• Assess rhythm regularity, extra sounds (S3, S4), murmurs (timing, grade, radiation).
• Lung: crackles, wheezes, decreased breath sounds.
• Abdomen: bowel sounds, bruits.
• Vascular: carotid/femoral bruits.

Auscultation provides qualitative diagnostic information; rate is quantified separately.