What is a stethoscope used for?

A stethoscope is an accoustic device that listens to sounds from within the body. It is used to hear heartbeats, or airflow in the lungs, or blood flow (as when determining the pulse rate).
The stethoscope is a device (commonly used by doctors) to listen to heart and lung sounds. He places two earpieces into his ears and places the other part of the stethoscope on the chest and he will then be able to heart the sound of your heart and lungs.