This month, you’re going to create a sound amplifying device. It hearkens back to the old tin can and string telephones from ages ago. If you have to ask what that is, go ask your parents.
A large metal spoon or a wire coat hanger
Thread (about four feet)
Cut two two-foot lengths of thread.
Tie them both to the handle of a big metal spoon (or the top part of a metal hanger).
Put the two ends of the strings on the tips of your two pointer fingers and put them into your ears along with the string.
As the spoon or hanger is hanging in front of you, knock it into the edge of a table to produce a “gong” sound.
The spoon, when it hits a surface, begins to vibrate. That’s what causes the air to vibrate and produce “sound” in our ears. When we attach the strings to this and tap them straight into your ears, the sound waves travel directly along the string and are brought directly into your ears. Sound travels better through a solid (like the spoon and string) than through the air.
Another experiment: (get your parent to help you with this part)
Get two empty metal soda cans and use a can opener to cut off the top ends (be careful of the sharp metal).
Punch a hole in the other end of the can.
Thread a long string through the cans and tie a big knot in the ends so it doesn’t slip off the can.
Pull the string tight by having you and a friend take each can. Whisper to each other, talk normally, etc. Experiment with the sound!
Will different types of spoons or objects hanging from your ears produce the same or better effects? Smaller spoons or larger spoons? Wooden spoons? A water bottle? Try them out and see which ones work the best. If you need an idea for a science fair project, this one would work out great as a test to see which types of materials produce the best sounds. Of course, you would have to find a way to measure the differences between the sounds, but I bet you could do it.
I hope you enjoyed these simple experiments. If you have more questions about this, specifically around the science fair aspect of this experiment, contact the author.
Steve Davala is a high school chemistry and physics teacher who likes to write and work with Photoshop. He’s got two kids of his own and subjects them to these science activities as guinea pigs. Follow him on Twitter, on www.stevedavala.blogspot.com or email him at firstname.lastname@example.org.