Stethoscope: An instrument that is used to transmit low-volume sounds such as a heartbeat (or intestinal, venous, or fetal sounds) to the ear of the listener. A stethoscope may consist of two ear pieces connected by means of flexible tubing to a diaphragm that is placed against the skin of the patient. The stethoscope has become one of the symbols of the medical profession. The origins of the stethoscope can be traced back to the French physician La'nnec, who in 1819 invented a crude model that consisted of a wooden box that served to help physicians hear the sounds within the chest cavity. It has undergone many modifications since then.