Heartbeat and Pulse Rate Biology Assignment

Rene Laennec of France invented the first stethoscope in 1816 to protect the modesty of one of his female patients. This first stethoscope was fashioned from several sheets of paper rolled to form a cylinder. Prior to this invention, physicians listened to heart and lung sounds by pressing an ear to their patient’s chest. The stethoscope increased the range of sounds that were audible and was more acceptable to patients. The earliest models were monaural (physicians listened with only one ear.) A variety of materials and designs were used in the attempt to conduct sound efficiently.

In 1837, Dr. Oliver Wendell Holmes returned from medical studies in Paris and urged his fellow American physicians to increase their use of stethoscopes. By the mid 1840s, the stethoscope had become integral to the practice of medicine in the United States.

11. Rene Laennec (1781-1826)
Inventor of the first stethoscope

Although numerous styles were introduced during the last half of the nineteenth century, by the 1860s most physicians had switched to the basic design that is used today. This stethoscope, designed by George Cammann, was binaural. Cammann found that “The power of conduction is greatly increased by the reception of the sounds simultaneously into both ears.” In addition to conducting sound more efficiently, a binaural instrument helps the listener block out external noise. The shape and composition of the ear and chest pieces have changed throughout the century, but the binaural style has remained. The two types of chest pieces used are the bell, which primarily transmits low sounds, and the diaphragm, which detects high frequency sounds. In 1926, the first workable combination of bell and diaphragm was designed and became the prototype for stethoscopes used today.