How Does a Stethoscope Work?


A stethoscope is one of the most familiar instruments used in modern medical care. The instrument makes it possible for a doctor to clearly listen to sounds inside the human body. This is important when diagnosing diseases.

As familiar as a stethoscope is, some people still wonder how it works.

A stethoscope comprises of different parts which make it simple for healthcare providers to use it on their patients. Below is an explanation of how the device works.

Parts of a Stethoscope

A regular stethoscope has a round flat disc. This part is normally held against the patient’s chest or other areas of the body with the aim of listening for sounds. On the disc, there is a tight, stretched-out plastic skin known as the of a stethoscope

The diaphragm is linked to a piece of long tubing, which is then linked to two, slightly shorter rubber tubes with fittings that are placed into your ears. The earpieces can either be made of modeled plastic or rubber.

See all parts of a stethoscope here.

How Does a Stethoscope Work?

A stethoscope is used to listen to sound waves in the body. The diaphragm registers internal sound waves felt against a patient’s skin. A doctor will hold the chestpiece on the patient’s chest and sound waves will then vibrate the diaphragm.

The stethoscope also has hollow acoustic tubes that are thinner than the diaphragm. These tubes magnify sound in a process known as multiple reflection. Sound is conveyed through the tubing to the earpieces.

The earpieces don’t have a diaphragm. Instead, the eardrum acts as the diaphragm by vibrating to the sound waves caused by changes in air pressure.

If you press the chestpiece lightly against the body, you will hear low frequency sounds. If you tightly press the chestpiece against the body, the diaphragm will be able to pick high frequency sounds.

Some stethoscopes are designed with a bell (a smaller diaphragm) on the opposite part of the diaphragm. A good example of these are pediatric stethoscopes. The bell and diaphragm are used to auscultate the sound waves in a child’s body. The bell is used to transmit low-pitched sounds while the diaphragm is used to transmit high-pitched sounds.

Facts about Stethoscopes

  • Stethoscopes comprise of seven different parts; the diaphragm, the chest piece, the stem (links the diaphragm to the tubing), the headset, the acoustic tubes and the earpieces.
  • The different parts of the stethoscope are assembled by hand to ensure that every piece is airtight. This is done to improve their functioning.
  • Stethoscopes require some care and maintenance to maintain their airtight properties and continue conducting sound waves efficiently.

Although doctors have different kinds of high-tech medical instruments that can diagnose problems in the body, stethoscopes are among the most valued equipment for patient diagnosis.

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