Help Your Child Make Their Own Stethoscope

Learn about sound and the human heart.

It's surprisingly easy to make a usable stethoscope that will allow your child to hear his or her own heartbeat. And, of course, your child can learn a lot from the experience of listening to a heartbeat. Real stethoscopes are very expensive, but this simple project costs almost nothing.

Building a stethoscope is a great way get your child into hands-on science. It can a school project, or just a way to explore healthy Heart activities or answer questions about doctor visits. Once your child has built a stethoscope, she'll be able to hear the difference between his resting and active heart rates as well as the difference between the sound of his heart rate and that of other people in your house.

Materials Needed

A stethoscope.
A stethoscope. Peter Dazeley/Getty Images

To build your stethoscope, you'll need:

  • a flexible tube (a Slinky Pop Toob toy is ideal, but an ordinary rubber hose, tube, or a foot-long piece of dryer vent tubing will work, too)
  • small funnel
  • duct tape
  • a medium-size balloon
  • scissors

Thinking About the Science Behind Your Stethoscope

Ask your child the following questions to help her formulate a hypothesis about why a stethoscope might work better than listening with a naked ear to the heartbeat:

  • How does a doctor hear your heartbeat?
  • Why do you think a stethoscope works?
  • How do you think we’ll be using these materials to make your own stethoscope?
  • What do you think we'll hear when we listen to your heart?
  • Do you think your heart will sound different from mine?
  • How do you think your heartbeat will change after you do 20 jumping jacks?

 

Make the Stethoscope

Follow these steps to construct your stethoscope. Allow your child to do as much for him or herself as possible.

  1. Put the small end of the funnel in one end of the flexible tube. Push the funnel as far you can into the tube to ensure a snug fit.
  2. Tape the funnel into place using duct tape. (we used bright green duct tape for our stethoscope, but any color works just as well.)
  3. Inflate the balloon to stretch it out. Let the air out and then cut the neck off of the balloon.
  4. Stretch the remaining part of the balloon tightly over the open end of the funnel, duct taping it into place. This creates a tympanic membrane for your stethoscope. Now it's ready to use.
  5. Place the funnel end of the stethoscope on your child’s heart and the end of the tube to his ear.

Questions to Ask

Encourage your child to use the stethoscope to ask and answer the following questions:

  • Why did we put the balloon on the funnel?
  • What do you hear with your stethoscope?
  • How fast is your heart beating?
  • Jog around the house or run in place for a few minutes and listen again. Do you hear a difference?
  • Does your heart beat faster or slower than an adult’s heart Why?
  • Is there a difference in your heartbeat versus that of another child close to your age?

What's Going On?

The homemade stethoscope helps your child hear his heart better because the tube and funnel amplify and focus sound waves. Adding a tympanic membrane also helps to amplify the vibrations of the sound waves.

Extend the Learning

  • Listen carefully: Do you hear one sound or two sounds in your heartbeat? You should hear two: a long, lower sound and a short, higher sound. The sounds are made by different sets of valves letting blood in and out of your heart.
  • Try using the stethoscope to listen closely to different sounds. How does the refrigerator sound through a stethoscope? Try listening to a pet's heart, or to a cat's purr.