Listen and Learn: DIY Stethoscope Experiment for Children

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If your child is ever curious about those funny tubes that doctors use to listen to their heart, I’ve got a great experiment to pair engineering, science, and help with their curiosity!

In today’s experiment, we’re going to walk through how to create a stethoscope with your child, which is a fun and educational activity that will help them learn about sound waves, how to engineer simple devices, and even a little bit of anatomy.

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How to make the Listen and Learn Stethoscope engineering experiment

Supplies you will need

For this experiment, you will need the following:

• 2 funnel cups
• 1 balloon
• 1 straw
• Scissors
• Tape

Here’s a fun kid’s book about the five senses that you can use to accompany this experiment!

Before you start

Since we’re using scissors to cut the balloon, please keep an eye on your child.

Instructions

Here is how to do this experiment:

Step 1: Cut the balloon

First, we’re going to cut the neck of the balloon so that we can stretch it over the wide end of one of our funnel cups.

It’s best to cut closer to the balloon opening and make adjustments as needed so you do not cut too much of the balloon off.

Step 2: Stretch the balloon over the funnel cup

Stretch the balloon over the wide end of one of the funnel cups. Handle the balloon carefully, since it could rip if it’s stretched too far.

Once your balloon is attached, secure it with tape to make an air-tight seal.

Get your child involved: If your child has grip strength, allow them to try to stretch the balloon over the funnel cup! It’s a great fine motor exercise.

Step 3: Attach the straw to the funnel cups

Insert your straw into the small end of one of the funnel cups and wrap it with tape to create a seal. If your straw doesn’t quite fit inside the small end of the funnel cup, just use enough tape to ensure a seal with them butted up to one another.

Repeat this with the other funnel cup. Now your stethoscope is complete!

Get your child involved: Here’s another great fine motor skill exercise for your child. Have them insert the straw into the small end of the funnel cup and you can add on the tape!

Step 4: Listen to your heartbeat!

When your child places the funnel cup against their body, it creates an airtight seal. As they press on the balloon, the air pressure in the funnel cup changes, which sends sound waves through the funnel cup, into the straw, and into their ears. This allows them to hear the sound of their heartbeat, their breath, or even the sound of their own voice.

If it’s tough to hear your heartbeat, run around the house for a minute to get your heart rate up. That should do the trick!

The engineering behind the Listen and Learn Stethoscope experiment

This experiment teaches:

• Introduction to Sound Waves
• Hands-on Engineering
• Anatomy Awareness

How it works

This stethoscope STEM experiment is a pretty simple and fun way to introduce little ones to the concept of sound waves and basic engineering principles. Constructing a makeshift stethoscope using a few simple household items can teach children to explore the world of sound and anatomy.

By placing the funnel cup against your body and pressing on the balloon, an airtight seal is created. This seal allows sound waves to travel through the funnel cup and into the straw, which acts as a conduit or channel for the sound to reach your or your child’s ears through the earpieces attached to the straws.

Pressing on the balloon causes the air pressure inside the funnel cup to change. When that happens, it causes sound waves from your body to be transmitted and amplified.

This allows you to hear sounds that would be difficult to hear, such as your heartbeat or breath.

Introduction to Sound Waves

Start by discussing how sound is created by vibrations. Explain that when they speak, their vocal cords vibrate, creating sound waves. Similarly, their heartbeat and breath also produce vibrations. You could also use this experiment to actually see sound in the form of vibration!

Next, explain that sound waves need a medium to travel through. In this experiment, the air inside their body acts as the medium, and the stethoscope helps capture and transmit those sound waves to their ears.

Also, this is a great opportunity to show how a stethoscope amplifies sound. Together, place the funnel cup on different parts of your body, such as the chest or stomach, and listen to the different types of sounds your body makes. You can explain here that the stethoscope collects and focuses the sound waves, making them louder and easier to hear.

Finally, discuss how sound waves travel from the body to the ears through the stethoscope. Explain that when they press the balloon, it changes the air pressure inside the funnel cup, causing the sound waves to travel through the funnel cup, down the straw, and into their ears.

Hands-on Engineering

This engineering experiment is a great one to introduce engineering concepts and how to build things to your child because it uses only a few objects that are easy to manipulate and creates something that they’ve likely seen used before (like at the doctor’s office).

Depending on your child, they could easily be a part of the design process by figuring out how to attach the straws and stretch the balloon over the funnel cup. It’s also a great learning experience in problem-solving, since your balloon may rip, there may not be enough tape, or other potential hiccups in building your stethoscope.

This experiment is also a great opportunity to talk about some engineering principles. For example, if we do not create an airtight seal, we lose the ability to fully transmit the sound and hear it. They can also play around with changing the air pressure inside the funnel cup and how that affects the transmission of the sound waves.

Anatomy Awareness

Through this experiment, child can gain a basic understanding of human anatomy.

They discover that sounds produced within their bodies, such as heartbeat or breath, can be heard and explored using the stethoscope. This helps them connect the device to the study of the human body and increases their awareness of their own physiology.

You could take this a step further by listening to their heartbeat before and after running around for a few minutes. How does your heartbeat change after running around? Or listen to your belly after you’ve had lunch; can you hear your food digesting?

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More sound experiments to try out with your child

• Dancing Rice: Watch sound vibrations in rice and see what songs make your rice dance the most!
• Water Glass Music: The classic experiment with making music with water and glasses