How Does A Stethoscope Work?

A stethoscope is a common medical instrument used by doctors to listen to a patient's heart and lungs, measure blood pressure, and more. Stethoscopes were first invented more than 200 years ago and continue to be a vital piece of medical equipment today. According to Medicine Net, the first stethoscope dates back to the early 1800s and was made with a wooden box. You've likely seen your own doctor sporting one around their neck at an appointment. The instrument typically includes two ear pieces that connect to a tube and two-sided chest piece, but has been modified over the years. Stethoscopes are placed against the skin of the patient in order to hear low- or high-volume sounds, like a heartbeat or heart murmurs.

A lot can be revealed about someone's health thanks to a stethoscope. According to Science Direct, a stethoscope features two sides known as the bell and diaphragm. The diaphragm is used for high-frequency sounds, while the bell is used for low-frequency sounds. This allows doctors to hear the heartbeat rate and determine if it's irregular. Plus, a stethoscope is able to pick up wheezes in asthmatic patients or crackles in those with interstitial lung disease.

When a stethoscope is placed on a patient's chest, the diaphragm on the device vibrates from the sounds in your body, sending back sound through the tubes and into the ear pieces, Avacare Medical explains. This is when your doctor will be able to hear your heartbeat and if there are any murmurs present, depending on the side of the stethoscope used. For example, to hear heart murmurs, doctors will likely use the bell side of the stethoscope because it picks up low-frequency sounds. Each sound wave bounces off the tube's walls through a process known as multiple reflection.

While a stethoscope is primarily used to listen to the heart and lungs, there are many other uses as well. It's utilized to identify bowel sounds and detect abnormal blood flow, according to Inside First Aid. Blood flow issues can be identified through a specific "whoosh" sound through a stethoscope. You've also possibly seen your doctor use the stethoscope for measuring blood pressure. The stethoscope is used to listen to heartbeats directly underneath the blood pressure cuff.