Stethoscope - Understanding Its Parts and How It Works


Stethoscopes are one of a Respiratory Therapist’s most vital tools. They can help us identify whether a patient is having bronchospasm, retaining secretions in their airways, or if they’re having unilateral lung issues.


While we spend a lot of time studying the sounds we hear with a stethoscope, we often spend less time learning about the tool itself. In order to help you better understand the parts of a stethoscope and how they function, we’re going to breakdown the pieces of a stethoscope from top to bottom:

Parts of a Stethoscope Listed Out:

1. Ear tips
2. Ear tubes
3. Tubing
4. Chest Piece
5. Stem
6. Diaphragm
7. Bell

Keep reading for a detailed description of each stethoscope part.

Ear Tips

Ear tips are the plastic or silicone buds at the top of the stethoscope that rest in your ear. Most stethoscopes come with two or three different sizes of ear tips. Picking the wrong size of ear tips can affect the sounds you hear with a stethoscope.

A size too small can impair sound quality and a size that is too big can irritate your ears.

If you find that the earpieces that came with your stethoscope aren’t comfortable or don’t fit properly, there are several companies that sell ear tips of different shapes, sizes, and materials.

Keeping the ear tips clean is important. If they happen to become clogged with ear wax or debris, it can alter the sounds that you hear. This is why it’s important to clean the earpieces regularly with alcohol wipes.

Ear Tubes

The ear tubes are the metal pieces that connect the earpieces to the tubing of a stethoscope. They’re often made of steel.

This is the part of a stethoscope that is responsible for holding the ear tips and providing the left and right pathways for sound to travel through.

They contain tension springs that rest between the ear tubes. These springs enable you to adjust how tight your stethoscope is sitting on your ears by either pulling the ear tubes together or pushing them apart. You must adjust the tension to make a proper seal but not too much because you don’t want it to be uncomfortable during use.


There’s a lot more that goes into the tubing of a stethoscope other than pretty colors and designs. The tubing plays an important role it facilitates how the sounds travels from the chest piece to your ears.

Stethoscope tubing is typically made of PVC and it can have a single lumen or double lumen. Single lumen stethoscopes have one tube that connects directly to the chest piece and splits into left and right sides. Double lumen stethoscopes, on the other hand, have two individual tubes.

When choosing a stethoscope, you want to pick one with tubing that is thick enough to block out external sounds. If the tubing is too thin, it can impact the quality of sounds that your hear.

Tubing length is also important. In general, it’s best to select tubing that is 25 to 35 cm in length. Tubing that is shorter than 25 cm may not allow you to auscultate the patient from a comfortable distance. However, if the tubing is longer than 35 cm, this too can diminish the quality of sound that you hear.

If your stethoscope tubing becomes damaged, you can purchase replacement tubing rather than investing in a whole new stethoscope.

Chest Piece

The chest piece is sometimes referred to as the head of the stethoscopes. It’s the part that is placed on the patient’s body in order to hear sounds during auscultation. The chest piece is made up of the

  1. Stem
  2. Diaphragm
  3. Bell

Dual-sided chest pieces will have both a diaphragm and a bell, while a single-sided chest piece will only have a diaphragm. Modern stethoscopes typically have diaphragms and bells that are made of a metal base that sits around a plastic disk.

When placed against a patient’s skin or clothing, the sounds produced by a patient will make the plastic disk vibrate. It is these vibrations that are responsible for creating the sounds that you hear through the device.

Diaphragms are larger in diameter and pick up higher frequency noises such as breath sounds. The bell, on the other hand, is smaller and picks up lower frequency noises such as heart murmurs. Because bells are smaller, they are also often used to listen to the breath sounds of smaller pediatric patients.

The stem is the metal piece that connects the diaphragm and bell to the tubing. If you do own a dual sided stethoscope, this is the part that will enable you to rotate the head of the stethoscope and alternate between using the diaphragm and bell.

Some companies sell stethoscopes with diaphragms and bells that are hypoallergenic and non-chill materials to increase patient comfort.

How to Clean a Stethoscope?

The parts of the stethoscope, at times, are delicate. They are made of materials that can become damaged if they are cleaned improperly. That is why it’s important to know the proper techniques for cleaning a stethoscope. Here are some of the most common mistake users make when cleaning:

  • Immersing the stethoscope in any kind of fluid
  • Using hand sanitizer to cleanse the device
  • Using an autoclave for sterilization

You should avoid these if you want to avoid damaging your stethoscope.

To clean it properly, you should use 70% isopropyl alcohol, 2% bleach solution, or mild soap and water when cleansing your stethoscope. This can safely disinfect the device without damaging any of the materials.

To prevent spreading infection from patient to patient, you should wipe your stethoscope down between each patient contact.

What is the Best Stethoscope?

Our top recommendation is the 3M Littmann Classic III Stethoscope. It’s what we typically recommend for Respiratory Therapists, nurses, doctors, and students.

That is because it provides great quality and acoustics without breaking the bank. Be sure to read our full list of Best Stethoscopes for Medical Professionals.

Final Thoughts

As you can see, there’s a lot of key parts and pieces that make up a stethoscope. Again, these parts include the ear tips, ear tubes, diaphragm, bell, and the stem.

The quality of sound you hear from your stethoscope will depend on the quality of the parts that make up the device. Hopefully this article has helped you develop a better understanding of this topic.

So next time you go to listen to your patient with your second set of ears, remember that the pieces of your stethoscope are just as important as the sounds you hear with it.

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