Experiment
Pling in the bowl
Can you hear sound through a string? Try this simple and amazing experiment that explores the science of sound waves and how they propagate.
You need:
- Teaspoons
- Ruler or something that can be struck with. Preferably in wood.
- A string, about one meter long.
This is what you do:
Tie the spoon in the middle of the twine. Hold the ends of the twine and measure with the ruler. Listen to the sound. Twist the ends of the string around each index finger and insert the fingers into the ear. Beat the spoon again. Listen to the audio now! Why do you think the sound changes?
Explore further:
- How did it sound?
- Try hitting the spoon against the table. Does it sound different?
- Change the length of the string and try again. Did it change the sound?
- Use other metal kitchen equipment, such as a fork, strainer, grater and the like, instead of a spoon. Listen to the sound.
- How do you think the sound reaches your ears?
What is going on?
When the ruler hits the spoon, it creates vibrations that create sound waves. These sound waves travel up the string and to your ear instead of just spreading out into the air around you.
The string acts as a conductor - an object that allows sound waves to travel.
Depending on the size of the spoon and the length of the string, the sound will seem louder (like a church bell) or deeper (like a gong).
And because the string allows the sound waves to continue to travel, the sounds from the spoon will resonate or reverberate - meaning they will continue for some time after you hit the spoon.
Another thing we found was that the only person who can hear the bell or gong sound will be the person with the string close to their ears. Everyone else in the room will only hear a faint "tink" when the ruler hits the spoon.
