Make Your Own Stethoscope

In honor of healthcare workers, we will be making one of their most valuable tools used to fight disease...the stethoscope! The stethoscope allows a person to hear the workings of the body, most commonly the heart and lungs, from the outside.

The tool works with the bell chest piece, that picks up low sounds, a sensitive diaphragm, that picks up higher sounds, that work together to amplify sound down the length of a hollow tube that connects to the listener’s ears. This is due to the shape of the bell being a funnel shape that allows sound to bounce down the tube. Just as you may use a megaphone to amplify your voice over a long distance, the same phenomena is being used to listen to a heartbeat or breath.

Sounds are created by the vibration of an object that in turn disturb the medium, in this case the air and your ear drum. This proves that sound cannot move through a vacuum since no medium is present for the sound to disturb. Sound waves in air are longitudinal waves because particles of the medium through which the sound is transported vibrate parallel to the direction that the sound wave moves. Sound can also be considered a pressure wave since the areas of compression have high pressure (since a lot of particles are pushing closing on each other) and areas of rarefaction have low pressure (due to the molecules being able to spread out a bit more). You can observe this at home with a slinky! If you stretch out the slinky and move it back and forth on one end (not up and down) you will see a compression, or wave, go through.

When describing sound, amplitude is in relation to volume and frequency is in relation to the pitch (note). This can be seen when singing a note with the higher the pitch the more the throat vibrates (frequency).

Using materials at home, you will be able to hear what medical personnel hear when checking your heart and lungs.

Key Terms

Stethoscope - a medical instrument for listening to the action of someone's heart or breathing, typically having a small disk-shaped resonator that is placed against the chest, and two tubes connected to earpieces.

Diaphragm - a thin sheet of material forming a partition; a taut flexible membrane in mechanical or acoustic systems.

Amplify - increase the volume of (sound)

Wave - repeating and periodic disturbance that moves through a medium from one location to another

Frequency – the number of waves that pass through a point over a given amount of time; associated with the pitch (note) of a sound

Amplitude – the displacement of a wave; associated with the volume of a sound

Longitudinal – a wave in which the particles of the medium are displaced in a direction parallel to the direction of energy transport; a wave vibrating in the direction of its origin

Compression – the pushing together of molecules in a medium

Stethoscope Model #1

• 2 Balloons (1 will also work if that is all that is available)
• Cardboard Tube (Toilet Paper Roll OR Paper Towel Roll)
• Duct Tape
• Gorilla Tape
• Electric Tape OR other strong tape (other tape may be used, but the effect may not be as strong)
• Plastic or Metal Funnel (Paper will not work) Scissors Coloring Materials*

*If Desired

Stethoscope Model #2

• 2 Balloons
• Small Piece of Tubing (plastic or rubber)
• Tape
• Scissors
• 2 Funnels with ends able to fit within the tubing

If desired, decorate the tube with coloring materials.

If using a longer tube, cut down to the size of a toilet paper tube.

Insert the long end of the funnel into one open end of the tube. Secure tightly with tape around the tube and the funnel.

Cut the long section of the balloon (the section where air is blown into) and wrap around the tube part without the funnel. Make it as taught as possible and secure well with tape.

If two balloons are available, repeat previous step but wrap the balloon around the wide end of the funnel.

Insert the long end of one funnel into one end of the tubing. Repeat with the other funnel.

Tape the area around the opening of tube and the funnel ends as tight as possible.

Using the Scissors, cut the top end of 2 balloons off.

Take the balloon tops and stretch them over the large ends of the funnels

Tape the area around the edge of the stretched-out balloon and the funnel tightly with tape being sure to keep the balloon as taught as possible.

Ask a volunteer for permission to hear their heartbeat or their breath.

Take an end with the funnel and place it on the chest or back directly to the skin (or fur). Any extra clothing will muffle the sound.

Place your ear against the other end and listen CLOSELY to hear the volunteer’s heartbeat or breath. If using the Stethoscope Model #2, you will also be able to listen to your own heartbeat and breathing!

1. Listen to a volunteer’s heartbeat when at rest and after exercising.
2. Listen to a person’s breath when at rest and after exercising.

CrashCourse: The Science ofSound

https://www.youtube.com/watch?v=qV4lR9EWGlY

SciShow Kids: What is Sound?

https://www.youtube.com/watch?v=3-xKZKxXuu0

How Sound Works (in rooms)

https://www.youtube.com/watch?v=JPYt10zrclQ

TedEd: How the Stethoscope was Invented

https://www.youtube.com/watch?v=0bxiOMJAMW8

TedEd: The Science of Hearing

https://www.youtube.com/watch?v=LkGOGzpbrCk

DocUnlock: Why Do Doctors Use a Stethoscope?

https://www.youtube.com/watch?v=WRrCGs0Q98c