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During this Month of Sound we’ve made a couple of instruments that have helped us experiment with sound. This week we’ll make one final instrument to round out your homemade orchestra. You have a flute and a kazoo and now it’s time to add in the brass section with a homemade horn!
Materials:
- A disposable rubber glove
- A plastic drinking straw
- A plastic water bottle
- A pair of scissors
- A rubber band
- Masking tape or painter's tape
Process:
- Snip a tiny hole in one of the fingers on the glove. Cut a few inches off of the straw and insert your new piece of straw in the hole. Tape it in tightly!
- Cut off the bottom of the plastic bottle. Have an adult help you make it even so it doesn’t snag or cut your skin.
- Put the glove over the top of the plastic bottle and wrap the rubber band around it to hold it as tightly as possible. You don’t want any air to be able to leak out!
- Hold your new horn so that the straw is in your mouth and the water bottle faces straight up and then blow through the straw. You’ll hear a loud foghorn sound!
Summary:
How loud can you play your horn?
With the glove tightly attached to the nozzle of the bottle and bent upward toward your mouth, not all the air you blow into it gets out at the same time. Since the glove is made of a stretchy, or elastic, material, it stretches out, lets some air through, and then contracts, or gets smaller again, and then stretches out to let more air through. This cycle repeats as long as you are blowing into it, but it happens very quickly, which makes part of the glove vibrate, which creates sound waves that travel into the water bottle. The sound vibrates the bottle and the air inside it, which creates resonance, more than one sound wave vibrating at the same frequency and making each other louder, which is why the horn is so loud.
Unlike your other instruments, your horn can’t change pitch to create different notes. But if you want a horn with a lower note, just cut the top and bottom off a second plastic bottle so you have a hollow tube and tape it onto the bottom of your first tube. Since it’s larger, it will vibrate more slowly and resonate with a deeper sound. If you cut the first bottle extra short it will vibrate faster, creating a higher sound. How many different kinds of horns can you make?
Want more Saturday Science? See all of our at-home activities on the blog or on Pinterest.
