stethoscope
Meaning of stethoscope: A hollow tube and a taut membrane, unchanged in principle since its invention, and still the fastest way to hear inside a chest.
Definition of stethoscope
A stethoscope is an instrument that carries sounds from inside the body to the ears of the person listening. A chest piece rested on the skin picks the sound up, and it travels along hollow tubing to the earpieces. It is used to listen to the heart, the lungs and the gut, and to hear the tapping sounds that mark a blood pressure reading.
How does it pick up sound?
The chest piece does the work. Its flat face is a stretched membrane, called the diaphragm, which vibrates with the skin and favors higher pitched sounds such as normal heart sounds, breathing and gut activity. The cupped face, the bell, is an open ring that sits lightly on the skin and passes lower pitched sounds, including some murmurs and the extra heart sound heard in a failing heart. Pressing the bell down hard stretches the skin beneath it and makes it behave like a diaphragm, which is why light contact matters. Many single sided chest pieces now use one tunable membrane that switches between the two behaviors with pressure alone. From there the sound is simply a pressure wave in a column of air, so long tubing, a poor seal at the ears, listening through clothing, or fingers rubbing the tube all degrade what arrives.
What is it used to listen to?
| Target | What is being listened for |
|---|---|
| Heart | Valve closure sounds, murmurs, rubs, and the extra sounds of congestive heart failure |
| Lungs | Air entry, wheeze, crackles and the friction rub of an inflamed lining |
| Abdomen | Whether the bowel is making sound, and how much |
| Arteries | The rushing noise of turbulent flow, and the tapping sounds used to read blood pressure with a cuff |
How do electronic and acoustic models differ?
An acoustic stethoscope is entirely passive. Nothing is added to the sound, and whatever is lost along the tubing is lost for good. An electronic model converts the vibration into an electrical signal, then amplifies it, filters out room noise and can record it or send it elsewhere. That makes faint sounds audible and helps a listener with reduced hearing, at the cost of batteries, more weight and an unfamiliar tone that takes practice to read. Neither kind produces an image, and neither identifies a diagnosis on its own. What the instrument delivers is the raw sound, and the interpretation belongs entirely to the person at the earpieces.
Used in a sentence
The clinician placed the stethoscope over the upper chest.
Good to know
An acoustic stethoscope only carries sound along a column of air, while an electronic one converts it into an electrical signal that can be amplified, filtered and recorded, which is why the two do not sound alike.
Word origin
Where “stethoscope” comes from
From Greek stethos, meaning chest, and skopein, meaning to examine or look at.