What is the Medical term meaning an instrument for listening to the heart and lungs?

Doctors use a stethoscope to listen to an animal's or human's internal sounds, such as the heartbeat or lungs.

Stethoscope.

Stethoscope

A stethoscope

Stethoscope

A stehoscope would be the most common instrument used.

A Stethoscope.

Stethoscope.

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I think the term you're looking for is Auscultation, listening to internal sounds of the body with stethoscope. (source: med school)