Stethoscope.
Is a tool that doctors use to listen to the inside of the body. Listen to your heart and lungs, mainly used in ancient Greece, Hippocrates used to touch my ears to listen to the voice of chest patients directly to the ad 1816 Dr. Ren Connect (Rene Lane Laennec) the French were using cardboard roll cylinder stethoscope which found that hear clear than the ears attached. He later changed to use a hollow cylinders mounted wood cone fit cylinder end use attached side chest patients. That sound you hear more clearly. Equipment in the popular medical era. After the machine has been developed continuously. At present, there is an electronic stethoscope wireless transmit data to the computer. And some models can record audio signals the internal organs of the patient