For a medical practitioner to determine what is going on to the patientís body, he would always need tools and equipment whenever taking diagnostic procedure. The medical instruments are usually categorized according to their function, either for invasive or non-invasive examination procedure. For the non-invasive medical instrument, the stethoscopes are among the physicianís most commonly used diagnostic instruments.
Before the invention of stethoscopes, physicians used to practice "immediate auscultation" wherein they literally place their ears directly on the patientís chest or back to listen for the sounds of congestion in the lungs and irregular heartbeats. But intimate contact to diagnose a sick patient is very risky for the part of the physicians as they may be infected with communicable diseases. And for the part of the patient, it is a little bit discomforting especially if a male doctor is examining a female physician.
In the early 19th century, a French physician Rene Theophile Hyacinthe Laennec discovered that it is also possible to hear internal sounds using a tube. At first, he made an improvised tube out of several sheets of paper. With the positive result that the said listening medical instrument brings, Laennec then perfected it using wooden materials. The wooden ausculatator that Laennec invented was called stethoscope, which combining the Greek words stethos (for chest) and scope (to view).
Along with the advancements in technology, the said medical instrument used for auscultation is also improved. And if you will see, the stethoscopes being sold nowadays have a bell-shaped device with a clear plastic diaphragm that is placed directly on a patientís chest or back, a length of rubber tubing that connects the diaphragm to a hollow metal headset with dual plastic earpieces in order for the examiner to hear the sounds from the chest cavity every time the patient breaths.
Aside from the sounds of congestion in the lungs, heartbeats of a person or even of the developing baby inside the motherís womb can also be heard using the same medical instrument for respiratory check up. The flat surface of the stethoscopeís diaphragm is used when examining flat body surface like chest and back as well as in listening high pitch sound. Meanwhile, the bell is used when hearing internal sounds from rounded surface like stomach. Moreover, bell is used to hear low pitch sound. But if you put pressure on the bell, this will pick up higher pitch sounds.