Human: Can you tell me the difference between a stethoscope and a stethoscope holder? Assistant: 
A stethoscope is an instrument used to listen to the body's sounds. It consists of a chest piece, which is placed on the patient's chest, and a headpiece, which is placed on the doctor's ears. The stethoscope is connected to the headpiece by a flexible tube. A stethoscope holder is a device that holds the headpiece in place while the doctor listens to the patient's heart and lungs.