Stethoscope. How Stuff Works

Stethoscope is a medical diagnostic tool for Auscultation which is the listening of internal sounds of the body. Auscultation is used to examine the heart sounds, breath sounds, bowel sounds etc. Auscultation requires skill,  clinical experience and a good quality stethoscope. An experienced physician can distinguish normal Lub and Dub sounds of the heart as well as heart murmurs and gallops. In combination with the sphygmomanometer, the Stethoscope is used to measure the blood pressure. The Stethoscope was invented by Rene Laennec of France in 1816. The two-sided stethoscope was invented by Rappaport and Sprague in the early 20th century.

The Stethoscope transmits the sound from the Chest piece through air filled hollow tubes to the ears. The Chest piece has two sides. A diaphragm side and a Bell. The diaphragm is a plastic disc while the Bell is a hollow metal cup. When the diaphragm is placed close to the chest, the body vibration produces acoustic pressure waves which pass through the hollow tubes to the listener’s ears. The Diaphragm passes higher frequency sounds. On the other hand, if the bell is placed on the chest, the vibrations of the skin directly produce acoustic waves which pass into the ear of the listener. The bell transmits low frequency sounds.

Stethoscope components are made of plastic and rubber, so that it can be damages easily if handled carelessly.