In 1816, 35-year-old Rene Theophile Laennec, a French doctor invented the Stethoscope - used to explore the respiratory, circulatory and digestive systems, by listening to the sounds coming from the heart, lungs and gut.
Laennec's model was little more than a wooden cylinder. This was based on an idea he had after coming across a group of children playing with a log of wood. With one child tapping and scratching at one end, the others would press their ears against the wood to listen to the sounds. Laennec utilised the same principle, by rolling a few sheets of paper into a cylinder and positioning it on the patient's chest, he found that he could hear heart pulsations much more clearly than before.
In 1828 an earpiece and trumpet shaped chestpiece were added. Finally in 1850 two earpieces were added and the binaural stethoscope took the form which we can see in modern day stethoscopes.
Most modern stethoscopes have a combined bell and diaphragm chestpiece made of stainless steel. The bell is for listening to frequencies in the range of 30 to 500Hz and the diaphragm for frequencies between 200 and 1400Hz. The doctor selects either side of the chestpiece by turning it in relation to the collecting tube which takes the sound up to the earpieces. The collecting tubes are made of flexible plastic and the earpieces are made of stainless steel.
