A stethoscope (from Greek stethos, "chest", and scope of ancient Greek "skopein," observe ") is an acoustic medical device, used for auscultation, that is to say the listening to internal sounds in the human body.

The stethoscope was invented in France in 1816 by Dr. Rene Laennec. It was only a question of a simple bundle of rolled paper, allowing to remove the ear of the patient's physician for reasons of modesty. He created auscultation mediate vs. immediate auscultation where he had his head stuck in the patient's chest. The first written description of its system dates back to March 8, 1817. Laennec secondarily constructed in several models of wood.

The model was improved in 1830 by Pierre Piorry who built an adapter ivory atrial side. Around the same time, a flexible tube connects the pavilion to the listener but the rigid model will still persist a few decades.

The stethoscope bi-atrial (both ears) was conceived in 1829 but built only in 1851. The tube was made of rubber but this solution proved fragile and had to be abandoned. A second model, more rigid, was born in 1852 in base metal tubes.

Around 1870, stethoscopes differentials appear: two pavilions, each mounted on a tube and connected to an ear, were used to compare auscultation in two different places.

In 1961, Dr. David Littmann Stethoscope created the contemporary chalet with its double reverse, which is still used today.

The stethoscope contemporary
Currently, stethoscopes have one or two houses, provided with a metal membrane that is applied to the skin of the patient. This membrane vibrated by the sound body, is connected by one or two flexible tubes to the operator ends up in his ears. The rigidity of the system at atrial, is done with a metal frame: the lyre. By its construction, it is an acoustic amplifier (large pavilion, small headphones). Sensors can filter certain frequencies to gather sound more specifically acute or severe, depending on the diagnosis to be made. Models with electronic amplification have been built, with no real commercial success.

The stethoscope is used by health professionals to listen to the heartbeat, the respiratory murmur, the thrill arterial or fetal abdominal sounds, or used in the measurement of blood pressure.

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