How to make your own stethoscope

Hear anyone’s heartbeat with this DIY stethoscope that uses tubing and funnels during British Science Week 2020

1. Stretch a balloon

First, cut off around one-third of a balloon from the open end, and stretch the rest of it over a small funnel. If you don’t have a balloon, you can also use plastic wrap.

2. Secure it in place

Use some strong tape to secure the covering in place – the more secure your covering, the more effectively it will transfer the vibrations of a heartbeat into a sound you can hear.

3. Add some tubing

Cut a 40-centimetre length of clear, plastic tubing – you can get it in a hardware or garden supply shop. Push the narrow end of the funnel into the tube, and secure it tightly.

4. Add another funnel

Add another funnel at the other end of the tube. You don’t have to cover this end with another balloon, but you can if you like. Why not try it without, then add a covering if needed.

5. Make it secure

Add another funnel at the other end of the tube. You don’t have to cover this end with another balloon, but you can if you like. Why not try it without, then add a covering if needed.

6. Test it out

Put the covered end of the stethoscope over your heart and the other end over your ear. What can you hear? Try it on other people, and on different parts of your body, like your neck.

7. Record your heart rate

If you have a stopwatch, you can record your heart rate. Start the stopwatch and start counting the number of beats in 60 seconds. Try running around for a minute and do it again.

Summary…

As your heart pumps blood around your body, valves in the heart open and close. These valves cause vibrations that a stethoscope can detect. They cause the membrane – the balloon – to vibrate, which causes vibrations in the air inside the stethoscope. These vibrations travel down the air in the tube and your ear picks them up. As you exercise, the heart beats faster to transfer more blood around your body.


This article was originally published in How It Works issue 133


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