diaphragm of stethoscope?

Question

define diaphragm of stethoscope

Answer 1

Many stethoscopes have a flat side of the head which is the diagphragm (for hearing high frequencies) and opposite side that is a "bell."

Link below has a picture.

Aloha

Answer 2

The way in which a stethoscope works is that a tube carries air pressure waves directly to the eardrum. Because the tube seals in the ear canal, small pressure waves transmit fairly efficiently and you can hear them.

In order to amplify sound, the other end of the tube flares out. A metal head on the end of the tubing acts as a funnel. The broad end of the funnel is held against the patient's chest, and the small end of the funnel plugs into the tubing. When small vibrations in the patient's chest wall occur, the funnel effect concentrates the energy into the tubing. Since the cross-sectional area decreases, the size of the vibration increases! This means the sound waves are actually amplified.

Most stethoscopes have a double head. On one side is a "bell" or open funnel. If you rotate the bell into the active position, you can actually look up the hole and into the tubing. The bell side is best for picking up low tones.

On the other side is a broader, flatter funnel, and over the opening is stretched a thin plastic sheet called the "diaphragm". The job of the diaphragm is just like the job of the skin on a drum. It vibrates. However, it does so, cleanly and crisply - all at the same time. When you put the bell directly on the skin, it may be that one part of the skin is moving more than another, there may be hairs interfering, the seal to the chest may be imperfect and pressure may be lost, decreasing the amount of transmitted sound. The diaphragm eliminates all of that by being an already closed space. However, just like anything that vibrates, it has a preferred frequency, and therefore it tends to emphasize the higher notes.

The diaphragm side is generally more useful than the bell, unless you are trying to diagnose subtle heart malformations. The diaphragm will give excellent heart tones, lung sounds, abdominal noises, and it is more than adequate to listen to blood vessels. Many modern stethoscopes don't even come with a bell anymore unless they are designated as "cardiology" type.

If you are going to purchase a stethoscope, don't skimp. This is a wonderful piece of diagnostic instrumentation and the difference between high and low quality is OBVIOUS when you compare them side by side. With a crappy one, you can barely confirm that your patient has a heartbeat, but with a great one, you can not only diagnose lung consolidation, but you can accurately tell which lobe it's in!

I hope that helps.