[The invention and evolution of the stethoscope].

There is a record of direct auscultation in the Hippocratic Corpus and this auscultation method has been used for more than 2000 years. In 1816, the first monaural stethoscope was invented by a French physician Dr. Rene Laennec, who also wrote books introducing how to use the stethoscope and auscultation. This instrument has been improved by several doctors and in 1851,the one improved by George Cammann, an American doctor, was the model of today's stethoscope. The electrical stethoscope was produced by the 3M(TM) Littmann Company in 1999, after which the audio files could be saved. In 2000, the vibration response imaging system was introduced into medicine. In 2006, a noise-free active stethoscope was displayed in the Acoustics Conference held in Honolulu, USA. This kind of stethoscope could be used in noisy or bumpy circumstances. These new pieces of equipment made the stethoscope's application field even broader.