Stethoscopes - what the doctor listens for

Written by: 
Dr Roger Henderson

It's one of the most widely recognised symbols of medicine worn around the necks of most doctors, but what do they listen for through the stethoscope?

The stethoscope is an instrument used by doctors and other health professionals to listen to body sounds. It is mainly designed to listen to the lungs and heart, although it is also used to listen to the bowels and bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. flow in other parts of the body.

Most stethoscopes are designed from Y-shaped rubber tubing that allows sound to enter at one end and heard through earpieces at the other. Many modern stethoscopes have a two-sided sound-detecting head that can be reversed, allowing high or low frequencies to be heard, depending which side is used.

Lub-dubs and wooshes

Listening to the lungs requires different listening skills from those used when listening to the heart. Normal heart sounds are often described as 'lub-dub', and are caused by the beating of the heart.

Sometimes 'whooshing' sounds called heart 'murmurs' are heard, caused by irregularities in bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. flow through the heart. These may be loud, or so faint that they are scarcely audible. Many people have heart murmurs that are harmless and cause no health problems, though sometimes a murmurA sound produced by the turbulent blood flow within the heart or arteries, heard with a stethoscope. is a sign of a heart problem that needs treatment.

A stethoscope is also used to listen to the pulse in the arm during blood pressure measurement.

Wheezes and crackles

When examining the lungs with a stethoscope, a doctor will listen for wheezes and crackles. Wheezes occur when the airways are constricted, and crackles occur when there is fluid in the lungs. These sounds should not be present in normal lungs.

The stethoscope is placed on the chest over the lungs and the patient breathes slowly in and out. This is repeated with the stethoscope placed on different parts of the chest.


Sometimes a doctor will use a stethoscope to listen to the abdomenThe part of the body that contains the stomach, intestines, liver, gallbladder and other organs. for the gurgling sounds of bowel activity. These are called borborygmi and they are completely normal, being produced by the movement of food and gas.

There are no risks involved and it is painless having a health professional listen to parts of the body with a stethoscope. It gives valuable clinical information that can help to confirm normal body functions or make a diagnosisThe process of determining which condition a patient may have. of the cause of health problems.