The stethoscope is a medical device used to listen to sounds produced in the human body. It is mostly used to listen to a persons breathing or the pounding of the heart. It is also used to listen to intestines as well as the flow of blood through the arteries and veins.
The stethoscope was invented by René-Théophile-Hyacinthe Laënnec in 1816 in France. This was monaural and was made of wood. The binaural stethoscope was invented in 1851 and is the standard design followed till today. Differential stethoscopes that could create a slight stereo effect were invented by 1853. These weren’t very popular with medical practitioners. There are two basic types of stethoscopes - acoustic and electronic. Acoustic stethoscopes are well known; they operate by transmitting sound from the chestpiece, through the hollow tube, and finally into the listeners ears. There are two parts to the chestpiece i.e.: the diaphragm and the bell, either of which could be placed against the body. The bell emits low frequency sounds, while the diaphragm emits high frequency sounds. This two sided stethoscope was developed by Rappaport and Sprague in the early 1920s. The sound level of the acoustic stethoscope is extremely low, making diagnosis difficult.
The electronic stethoscope increases the level of the sound by amplifying it. It converts the analog sounds made by the body into digital signals, which can then be amplified and processed. The simplest form of this type of stethoscope is a microphone placed against the body. This is not full proof as it picks up ambient sounds as well. The latest stethoscopes make use of a piezoelectric crystal. This is placed on the head of a metal shaft; the other end of the shaft is in contact with diaphragm.
The stethoscope is used to diagnose various dieses and conditions in patients. Before the use of stethoscopes, doctors used to place their ears on the patients body hoping to hear something. They are symbolic to the overall look of a doctor, as doctors are often seen with a stethoscope round their neck. Stethoscopes are also used by mechanics to isolate particular sounds of running engines to detect malfunctions. | 
