The stethoscope was invented by Rene Laennec, a Frenchman, way back in 1816. It came about thanks to Laennec being too much of a gentleman to put his ear against a woman’s chest for cardiovascular observation.
He realised, after experimentation with a rolled-up notebook, that doctors and nurses could listen to a patient’s heartrate through a hollow tube without having to make physical contact with them.
Laennec’s first stethoscope was made from wood, appearing similar to the “ear trumpet” of the time. His invention allowed physicians to listen in on what was happening within the body, and in 1852 George Philip Cammann perfected the binaural stethoscope which is still used as part of modern medical equipment to this day!
So, how does a stethoscope work?
It’s all about vibrations.
The part of the stethoscope pushed against your chest or back, with its cold steel giving you shivers for a brief moment, is known as the bell.
The bell is flat and round, and is covered by a thin layer of plastic known as the diaphragm. The diaphragm vibrates as sound is produced within the body.
These vibrations travel from the bell, up the hollow tube which splits into two, and into hollow ear pieces to be heard as sound by the medical professional.
So, what does he/she actually hear?
According to this article, a healthy heartbeat makes two sounds – a lub sound and a dub sound.
Dr. Bhavani Balaravi, from Raleigh Cardiology in the United States, shares that the lub sound is created by the closure of the mitral and tricuspid valves almost simultaneously.
The dub sound is created after the blood leaves the heart and the aortic and pulmonary valves close.
Dr. Balaravi adds that stethoscopes are also used, “in conjunction with sphygmomanometers to determine a person’s blood pressure.”