STETHOSCOPE

Hi friends!!!

Stethoscope is a important medical devices used by doctors in their day to day activities. Therefore it is important for every healthcare professionals to know in detail about the technology of stethoscope.

Let’s get into the topic.

WHY
STETHOSCOPE?

Stethoscope
is a device used by clinicians and doctors to listen to the sound that is
coming out internally from the human body and to find blood pressure in veins
and arteries. Most modern stethoscopes are binaural, which means a instrument
intended for use in both ears.

The use of stethoscope started back since 1816.
It was invented by French Physician named Rene Laennec by using a long rolled
paper tube to funnel the patients sound from the chest to his ear rather than
directly placing his ear on patient’s chest. It provided a great improvement in
hearing both heart and lung sounds.

WHAT ARE
THE COMPONENTS OF STETHOSCOPE?

A
stethoscope consists of ear plugs, ear tube, binaural spring, flexible tubing, a steam
and a chest piece called resonator. (Diaphragm and Bell).

The
earplugs are attached to the binaural springs made of steel so that they fit
firmly in the ears. The ear plugs are made of plastic or silicon rubber. The
ear plugs are connected to the binaural spring through the ear tubes and the
flexible tube is connected to the chest piece through the steam. The chest
piece is made up of metal like aluminum, chrome plated brass or stainless
steel. 

The flexible tube is made up of polyvinyl chloride or latex rubber. The
flat diaphragm is formed from a flat, thin, rigid plastic disk that can be
Bakelite, an epoxy fiberglass compound 
or other suitable plastic. Now a days most of the stethoscopes have an
anti-chill ring attached to both sides of diaphragm which are more comfortable
for the patients and also it has better suction thus allows sounds to be heard
more clearly.

WHAT IS THE
TECHNOLOGY USED?

When a
diaphragm of stethoscope  is placed on
the chest of the patient, a vibration occurs at the flat surface of the
stethoscope, as a result of sound waves that is being generated from the
patient’s body. Those vibration would travel outward if the diaphragm is a standalone
device. But since it is connected to a tube in stethoscope, vibration is picked
up by the diaphragm and being protected externally to prevent the sound loss
and thereby channeled through the tube in a specific direction.

Inside the tube
a multiple collision tends to occur as a result of wave collision within the
wall of the tube, it is called MULTIPLE REFLECTION. This continues until the
sound reaches the listeners ear drum at the other end of the device. By this
way the high frequency sound waves produced by opening and closing of the
arteries vibrate the diaphragm and reach the listeners ears.

The working
principle of bell is different from that of the diaphragm. It has a smaller
surface area and it was designed in such a way that it detects and picks up
lower pitched sounds. These lower pitched sounds have harder time in vibrating
the larger surface of the diaphragm, but it still vibrates the skin as it moves outward. The bell picks up the vibration of the skin caused by the movement
rather than the vibration of the arteries which directly vibrates the diaphragm.

WHAT ARE
THE TYPES OF STETHOSCOPE?

ACOUSTIC
STETHOSCOPE

It is the
most commonly used type of stethoscope which works based on the transmission of
sound waves emanating from the round shaped resonator to the listeners ears
with the help of hollow tube. The round shaped resonator is placed against the
patient to hear the body organ sound. It consists of two parts, a diaphragm and
a bell. The diaphragm transmits high frequency sound while the bell transmits
low frequency sound.

ELECTRONIC
STETHOSCOPE

One problem with acoustic stethoscope is that its sound level is low. Electronic stethoscope uses advanced technology to overcome these low sound levels. It works
the same as acoustic stethoscope but it has some additional features like
amplifiers and speakers to amplify the low frequency sounds and to attenuate
the low and high frequency sounds. 

Electronic stethoscope converts acoustic sound waves obtained from chest piece into electronic signals which are then transmitted through a circuitry and processed for optimal listening. One disadvantage of electronic stethoscope is that it suffers from ambient noise interference. The circuitry also allows sound energy to be encoded and decoded to reduce the effect of ambient noise.

Electronic stethoscope has an option for wireless transmission of data and recording of sound clips for detailed examination.