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Stethoscope guide

By the Life in Good Form editors. Updated 2026-10-15.

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Classic or cardiology

Details are from Littmann's Classic III and Cardiology IV pages. Littmann says both use tubing without natural rubber latex or phthalate plasticizers.

How a tunable diaphragm works

On its Cardiology IV page, Littmann explains that a tunable diaphragm picks up different frequencies as you change pressure on the chestpiece: hold it lightly to hear low frequency sounds, and press a little more firmly for higher frequency sounds.

On a double-sided chestpiece, rotate it to open, or index, the side you want; when the diaphragm is open, the bell is closed. Listen in a quiet room when you can.

Getting a good fit and seal

• Point the eartips forward, toward your nose, so the eartubes line up with your ear canals, Littmann says.
• Choose your eartip size. Littmann includes small and large eartips in the box; use the size that fits comfortably and seals.
• Check for leaks. Littmann says these stethoscopes rely on an airtight seal; loose chestpiece parts, loose or cracked tubing, or poorly seated eartips can break it.
• Clear obstructions. Lint or dirt from a pocket can block the sound path, so clean the stethoscope routinely and cover the open bell with the removable diaphragm.

Cleaning and care

For the Classic III, Littmann recommends cleaning external parts between patient exams with 70% isopropyl alcohol wipes, and says not to use hand sanitizer, immerse the stethoscope, sterilize it, or store it in extreme heat. Removable parts such as the diaphragms and eartips should be fully dry before reassembly, and eartips must be firmly attached before use to prevent ear canal injury.

What you are listening for

The National Heart, Lung, and Blood Institute (NHLBI) says that when your heart beats it makes a lub-DUB sound, which you may have heard with a stethoscope. The lub is the sound of the valves between the atria and ventricles closing after the atria pump blood into the ventricles. The dub comes when the aortic and pulmonary valves close after the ventricles pump blood away from the heart.

To find a pulse without a monitor, NHLBI says to place your index and middle fingers on the artery on the inner wrist below the thumb, count the beats in 30 seconds and double it. At rest, NHLBI says a heart rate of 60 to 100 beats per minute is normal. When you exercise, NHLBI notes, your heart beats faster to get more oxygen to your muscles, so check a resting rate after sitting quietly rather than right after activity. NHLBI also explains that the heart's electrical system, called the cardiac conduction system, controls the rate and rhythm of each heartbeat.

Children and babies

Littmann does not recommend the Classic III for neonates; it points to the Classic II Infant for neonatal patients, while noting some neonatal specialists still find that model's bell and diaphragm too large for good surface contact. For pediatric patients, it lists the Classic II Pediatric with a 1.3-inch diaphragm.

Buying and safety notes

• Authorized dealers. Littmann warns that counterfeit Littmann stethoscopes exist and says to buy from authorized dealers.
• MRI. Littmann says the Classic III cannot be used during an MRI because it contains metal.
• Device record. The FDA's device identification record for the Classic III (model 5620C) lists it as over the counter, not sterile and not single use, under the product code for a manual stethoscope, a Class I device under 21 CFR 870.1875.

For caregivers checking vital signs at home, see our upper arm blood pressure monitor guide and pulse oximeter guide.

What to look for when you buy

Questions people ask

Which stethoscope is best for nursing students?

Many start with a dual-head model; Littmann says the Classic III is used by students and professionals.

How do I clean a stethoscope?

Littmann recommends 70% isopropyl alcohol wipes between patients for the Classic III, not hand sanitizer or soaking.

Which way should the eartips point?

Forward, toward your nose, so they line up with your ear canals.

What is a tunable diaphragm?

A diaphragm that picks up low sounds with light pressure and higher sounds with firmer pressure.

Do Littmann stethoscopes contain latex?

Littmann says the Classic III and Cardiology IV tubing does not contain natural rubber latex.

Sources

• Littmann Classic III Stethoscope (littmann.com), Littmann (Solventum)
• Littmann Cardiology IV Stethoscope (littmann.com), Littmann (Solventum)
• Global Unique Device Identification record: Littmann Classic III, model 5620C (file: https://api.fda.gov/device/udi.json), U.S. Food and Drug Administration (openFDA)
• How the Heart Beats (nhlbi.nih.gov), National Heart, Lung, and Blood Institute

Sources checked 2026-10-15.