What your doctor really listens for with a stethoscope

Preventive Care

by Baylor Scott & White Health

Apr 28, 2020

The stethoscope you see draped around your medical professional’s neck has long been an iconic symbol of care. While you probably know the stethoscope is used to listen to the heart and lungs, you may wonder what this vital tool can detect.

Bao H. Le, DO, an interventional cardiologist on the medical staff of Baylor Scott & White Clinic – College Station Rock Prairie, explains how the stethoscope has evolved over time and why doctors, nurses and respiratory therapists can’t live without it.

What is a stethoscope?

The stethoscope is a device that helps physicians or healthcare providers primarily to listen to the sounds generated internally by your heart, lungs and intestinal tract. It is also used to check blood pressure.

How did the stethoscope come about?

The stethoscope was invented in 1816 as the first effective non-invasive tool by French doctor Rene Theophile Hyacinthe Laënnec.

“Initially, physicians placed their ear directly on the patient to listen to the internal sounds,” Dr. Le said. “However, this technique required physical contact between the physician and patient. That could be awkward for both the physician and the patient, particularly female patients. So, to create a distance between a physician and a patient, they used a wooden tube to listen.”

The device began as just a simple tube, but it has evolved dramatically over the years.

Today’s stethoscopes use sound amplification and noise-canceling technology to let healthcare providers more easily hear heart and lung sounds, dampen external noise and store data electronically.

Why is it such an important tool?

“We listen to the heart and diagnose different diseases based on what we hear,” Dr. Le said. “Without the stethoscope, we couldn’t hear the heart directly. And most of what we do [as cardiologists] is listening to the heart.”

As a cardiologist, Dr. Le listens for several common abnormalities when using his stethoscope. Some of those are:

  • A narrow valve, possibly due to aortic stenosis. If the patient has this condition, the doctor will be able to hear the murmur and tell what kind of valve is in trouble and evaluate the severity of the problem.
  • Valve leakage. Doctors can hear the tell-tale sounds of a leaky valve and pinpoint which valve is leaking and the amount of blood leaking.
  • Arrhythmias. Physicians can hear if the patient has a normal heart rhythm or if the patient has an abnormal rhythm, called an arrhythmia, like atrial fibrillation.

The three main parts of a stethoscope


The headset comprises two ear tubes, tension springs and ear tips. The amplified sounds travel up the stethoscope’s tube to the earpieces.


The piece of the stethoscope placed on the patient’s skin responsible for conducting sound.


The device inside the chestpiece that allows the doctor to hear different frequency sounds.

There is much to be learned by your care team with a simple “take a deep breath in.” Simply listening in is often the first step on a path toward diagnosis and better health—all thanks to the stethoscope.

Questions? Find a doctor who can help. 

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