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Science project idea

Tissue box rubber band guitar: what changes the pitch?

Sound is made by vibration. A thin, tight or short rubber band vibrates faster and gives a higher note; a thick, loose or long one vibrates slower and gives a lower note. The hollow box makes the sound louder.

Make it yourself8 numbered steps, the materials and the science, all free.Go to the stepsGet a ready-made kitReady-made models, kits and spare parts in the store under Best Out of Waste.Browse Best Out of WasteAsk on WhatsAppAsk the head office whether a model or kit for this idea is available.Send a message

What it shows

Sound is made by vibration. A thin, tight or short rubber band vibrates faster and gives a higher note; a thick, loose or long one vibrates slower and gives a lower note. The hollow box makes the sound louder.

The science

When you pluck a band it vibrates back and forth, pushing the air and sending sound waves to your ears. How many times it vibrates each second is called the frequency, and a higher frequency sounds higher in pitch. Tighter and thinner bands spring back faster, so they vibrate at a higher frequency. The air inside the box also vibrates, which makes the sound louder, just like the body of a real guitar.

Materials

Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.

  • An empty tissue box or a shoebox with a hole cut in the lid (free)
  • Five or six rubber bands of different thickness
  • Two pencils to act as bridges
  • Tape

Safety

For this project: Rubber bands can snap back and sting; pluck gently and keep them away from the face.

Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.

All the safety rules

Step by step

8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.

  1. Stretch the rubber bands over the tissue box so each one crosses the hole, mixing thick and thin bands.

  2. Slide a pencil under the bands at each end of the hole to lift them off the box and act as bridges.

  3. Pluck each band and listen: the thin bands sound higher than the thick ones.

  4. Press a finger on one band halfway along and pluck the short half; it sounds higher than the whole band.

  5. Pull one band tighter with your other hand while plucking and hear the pitch rise.

  6. Pluck a band while it rests on a table, and then over the box, to compare how loud it sounds.

  7. Arrange the bands from lowest to highest note and try to play a simple tune.

  8. Write a chart of thick or thin, loose or tight, long or short, and whether each gave a high or low sound.

What you should see

A playable guitar with bands that give clearly different notes. Thinner, tighter and shorter bands give higher notes, and the sound is louder over the hollow box than on a flat table.

Viva questions

A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.

1What makes the sound when you pluck a band?

The band vibrates, and the vibrations travel through the air to your ears.

2How do you get a higher note from the same band?

Stretch it tighter or make the vibrating part shorter.

3Why is the sound louder with the box?

The box and the air inside it vibrate too, which makes the sound bigger.

4What is pitch?

How high or low a sound is; it depends on how fast the thing is vibrating.

Free ebook: Viva Questions for Science Projects

Take it further

Use a free phone tuner app to measure the frequency of each band and plot it against the band’s thickness.

Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.

Free ebooks for this project

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