Hi, my name is Priscilla and I’m the blog intern for Austin Children’s Museum. I’m going to show you how to make a cool musical instrument!
Audrey, the Programs Coordinator at the Austin Children’s Museum, decided to share her instructions with me.
What you’ll need:
- Plastic water bottle or yogurt cup
- Scissors or box cutter
- Drinking straw
- Paper towel tube or rolled up sheet of paper
- Rubber band
- Balloon or latex glove
- Poke a straw-sized hole at the top of the water bottle label, or in the side of the yogurt cup.
- Cut the water bottle in half. Skip this step if you’re using a yogurt cup.
- Roll up a sheet of paper into a tube and tape it together, or use a paper towel tube. The tube needs to fit inside the top opening of the water bottle. If you are using a yogurt cup, use the box cutter to cut a hole in the bottom that is big enough to snuggly fit around a paper towel tube.
- Cut two or three holes into the paper tube.
- Cut off the end of a balloon to make a sheet of rubber. Put the sheet of rubber on the top of the yogurt cup VERY TIGHTLY. You can also use latex gloves instead of a balloon.
- Place the paper tube inside the yogurt cup and tape it to the cup so no air leaks out. Make sure the tube is far enough inside the yogurt cup so that it touches the balloon. This is very important because this is how the vibrations are made.
- Insert the straw into the little hole you poked into the bottle
- If you want to make extra sure the balloon is sealed, secure the balloon with a rubber band around the yogurt cup.
- Now blow into the straw. If it doesn’t make a sound, adjust the tension of the balloon membrane so that it’s tighter. Again, make sure the tube is touching the membrane.
- Place your fingers over the holes in the tube to change the sound
The balloon serves as the vibrating membrane in the membranophone. When you blow into the straw, the air waves cause the balloon membrane to vibrate. The vibrations then travel down the paper tube to make a sound.
Similar to when you blow into your membranophone, when you beat a drum, the covering of the drum (the membrane) vibrates and makes a sound!
So what happens to the pitch when you cover some of the holes in the tube?
Pitch is how we hear sound as high or low.
The sound waves create an air column when they travel down and out the tube. Since vibrations slow down after time, the longer the air column, the slower the vibrations.
When you cover the holes, you are creating a shorter air column. This makes the vibrations happen faster. Faster vibrations produce a higher pitch and slower vibrations produce a lower pitch. Check out other fun crafts and science experiments at the Austin Children’s Museum blog.
-Priscilla, Austin Children's Museum