Can We See Sound?
Can we SEE sound and vibration? To explore cymatics, the study of sound and vibration made visible, my 4th graders created Chladni patterns with a tonoscope. In fact, the Chladni Patterns, Tonoscope, and Green Screen Magic made this an unforgettable introduction to sound. I had them record their Chladni patterns on their iPads and upload images and video to their Seesaw account. Then I used their videos and images to make a background video. This was an early activity in their sound unit meant to pique their curiosity, and boy did it! The green screen was up so the kids wanted to pretend they were in the sound waves…. here’s how it all happened.
Cymatics, The Study of Visible Sound
“In African tribes 1000 years ago, according to the Encyclopedia of Religion Vol. 4, fortunes were told using the taut skin of drums sprinkled with small grains. Leonardo Da Vinci (1452 -1519) noticed that vibrating a wooden table on which dust lay created various shapes. Ernst Chladni (1756-1827) discovered that when he used a sand-strewn brass plate, excited by a violin bow it would create geometric patterns. These patterns are now known as ‘Chladni Figures.'” More information can be found on this site.
Ernst Chladni, an 18th century German scientist and musician, conducted a famous experiment in which he showed how moving a violin bow against a metal plate covered with sand could visually display the movement of sound. You can read about Ernst Chladni here. The study of visible sound is called Cymatics. Take a look at how the patterns change with the pitches in the video below.
This has fascinated me for several years and I’ve been trying, with the help of our Naturalist at school, to create a Chladni plate and replicate this experiment. We haven’t been able to get our piece of metal to work yet. Bummer! We’ll keep trying; but in the meantime, I found this video and made a tonoscope.
Students Made a Tonoscope
A Tonoscope allows you to make the sound waves from your own voice visible. A vibrating membrane (balloon) spread with sand or salt will pick up sound waves and make visible the patterns these waves create at various tones. The Tonoscope device is made of plastic PVC pipe from a hardware store, a balloon, and sand or salt. It is simple to construct, easy to use, and a fun way to talk about the science of sound.
Students Used the Tonoscope to Create Chladni Patterns
To use a tonoscope to make your voice visible, spread some sand or salt on the surface of the balloon. Hold it level to the ground so that the sand does not fall off. Sing a tone into the opening of the scope and hold that note for a few seconds. Rather than blowing air directly into the mouthpiece make a sound into it, think “do re mi fa so la ti do.” You can even sing a song! You should start to see the sand move and fall into different geometric patterns. Now try singing a higher or lower tone and watch how the pattern changes. As the pitch of the note gets higher the frequency of the sound waves increase and the waves appear more “intense” or close together. As the frequency of the waves increase the patterns become more intricate. My students discovered the higher the note you sing, the more intricate the pattern will be.
Chladni Patterns, Tonoscope, and Green Screen Magic With 4th Grade
The green screen was up in my music room and the students wanted to pretend they were on the top of the surface feeling the sound waves. The video above is a combination of the Chladni patterns created on the tonoscope mixed with green screen magic in 4th grade. Since this was just a teaser for the upcoming sound unit, they only have a basic understanding of the way sound can be made visible. However, they get it! The higher the pitch, the more intricate the pattern and the lower the pitch, the less intricate the pattern. I love how the kids drove the learning in this project and wanted to use the green screen to demonstrate their understanding. It wasn’t even in my plans at all.
Questions From Students
Exit Ticket: as an exit ticket, some students used Seesaw to record any questions they had after this activity. Here are a few of their questions:
- How did the sound waves get to the salt?
- Why did it vibrate more with salt than with rice?
- Why do different sounds make different patterns?
- Is there a pattern for every pitch that is made?
- Are the patterns always the same for every pitch?
- Would the patterns be different or the same on a bigger surface?
- Can sound move brick?
- This was really cool. Can we do it again?
I love how my students are so at ease with technology and they are driving the learning. I just wish my classes were longer; we just get into it and have to stop. What about you? What have you done with Chladni patterns in your sound unit? I would love to hear how you lead your students deeper in their understanding of sound.
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