Written and maintained by CASRAI Editorial Board
Last updated
This page describes products and general use; it is not medical advice.
Stethoscopes fall into two regulatory families and three common chestpiece designs. The U.S. FDA treats a manual (acoustic) stethoscope as a Class I device and an electronic stethoscope as Class II, and chestpiece design (diaphragm-only, dual-head or tunable) decides which sound range a given acoustic model handles. This guide sets out those types side by side. For parts, acoustic principles and cleaning, see what a stethoscope is.
Who uses them: clinicians, nurses and other clinic staff, students in clinical training, and the buyers who stock exam rooms and medical supply stores.
What a stethoscope is
Under 21 CFR 870.1875, a manual stethoscope is “a mechanical device used to project the sounds associated with the heart, arteries, and veins and other internal organs.” An electronic stethoscope is “an electrically amplified device” used for the same purpose. Its purpose is auscultation: listening to internal body sounds.
Main stethoscope types
| Type | Typical use | Key difference | Source |
|---|---|---|---|
| Manual (acoustic), diaphragm-only chestpiece | General listening, mainly higher-frequency sounds | One-sided chestpiece with a diaphragm only | Riester Academy |
| Manual (acoustic), dual-head chestpiece | Listening across both lower and higher frequencies | Bell on one side, diaphragm on the other | Riester Academy |
| Manual (acoustic), tunable or pressure-sensitive diaphragm | Wider range of patients from one chestpiece | A one-sided chestpiece whose diaphragm can act as both a bell and a diaphragm | Riester Academy |
| Neonatal or baby-specific | Neonatal care | Designed specifically for babies | Riester Academy |
| Electronic (digital) | Listening with amplification; sounds can be filtered, recorded or transmitted | Converts acoustic sound waves from the chestpiece into electronic signals | 21 CFR 870.1875; Riester Academy |
Bell versus diaphragm
The bell is suited to lower-frequency sounds and the diaphragm to higher-frequency sounds. They also work differently: with the diaphragm, body sounds make the diaphragm vibrate; with the bell, the skin generates the vibrations that travel up the tubing.
Regulatory class: manual versus electronic
| Device | FDA class | Premarket notification |
|---|---|---|
| Manual stethoscope | Class I (general controls) | Exempt, subject to the limitations in 21 CFR 870.9 |
| Electronic stethoscope | Class II (special controls) | Exempt only when the device is a lung sound monitor, subject to 21 CFR 870.9 |
Source: 21 CFR 870.1875, checked 2026-10-30.
How to use a stethoscope: fit and chestpiece choice
Using a stethoscope starts with a comfortable fit. The eartubes are bendable so the eartips can be angled to match the user’s ear canals, and the eartubes can be pushed in or out so the fit is neither too loose nor too tight. Eartips come in different sizes to give a snug yet comfortable fit and an acoustic seal. On the chestpiece, the bell is the side for lower frequencies and the diaphragm the side for higher frequencies. Clinical technique, including where to place the chestpiece and how to interpret sounds, is taught in clinical training and is outside the scope of this page.
Common mistakes
- Assuming every chestpiece is two-sided: some are diaphragm-only, and some tunable ones act as both bell and diaphragm.
- Treating electronic and manual stethoscopes as the same regulatory class: they are classified differently under 21 CFR 870.1875.
- Using a loose or poorly angled eartip fit, which works against the acoustic seal the eartips are meant to create.
Safe use and handling basics
Cleaning between patients is covered in our stethoscope guide. For related exam-room instruments, see the guides on the aneroid sphygmomanometer, the blood pressure cuff and the reflex hammer. Diagnostic instruments are grouped under diagnostic, monitoring and imaging supplies.
FAQ
How do you use a stethoscope?
Start with the fit: the eartubes are bendable so the eartips can be angled to the ear canals, and the eartips come in several sizes for a snug yet comfortable fit. The bell side carries lower-frequency sounds and the diaphragm side higher-frequency sounds. Where to place it and what the sounds mean is clinical training, not covered here.
What is the difference between a manual and an electronic stethoscope?
A manual stethoscope is a mechanical device and is Class I; an electronic stethoscope is electrically amplified and is Class II under 21 CFR 870.1875.
Sources
- U.S. Code of Federal Regulations, 21 CFR 870.1875, Stethoscope: ecfr.gov, checked 2026-10-30.
- Riester Academy, Stethoscopes learning module (manufacturer educational page): academy.riester.de, checked 2026-10-30.
