The Digital Bits Science Labs are fun science experiments for young children. Kids, make sure you have an adult's permission before trying any of these science experiments.
Digital Bits Science Lab
Science Experiments for Kids, Parents and Teachers
Use a squeaky balloon to teach about air pressure, vocal cords and sound waves
Description:
One of the classic fun things to do with a balloon is to “squeak” it. This easy game is the result of some interesting science - air pressure and sound at the molecular level. This is also very similar to the way we use our vocal cords to speak.
Equipment needed:
Balloons
The Digital Bits Science Lab Experiment:
Blow up a balloon. Hold the mouth of the balloon in both hands. Stretch the mouth, pinching your fingers on the balloon while pulling them apart, as in the picture below.
As the air flows out of the balloon, you’ll hear a high-pitched, loud squeaking noise. You can adjust the tension on the balloon mouth, and the pitch and volume of the squeaking will change.
What’s happening here? Why does a balloon squeak when you stretch the mouth?
Stretching the mouth of the balloon makes a very tiny space for the air to flow out of the balloon. The air pressure of the balloon itself forces the air out the mouth, but because of the stretching, that space is limited. The airflow causes the balloon mouth (the stretched part) to vibrate. The vibration makes the noise.
Put your hand on your upper neck - right under your jaw - and hum. You’ll be able to feel a vibration, similar to the vibration at the mouth of the balloon. This is air being forced over your tightly-stretched vocal cords. Remember how tightening or loosening the balloon mouth changed the sound of the squeaking? Hum in a high pitch and feel your neck. Hum in a low pitch, and the vibration will change.
You talk using a similar method to the way the balloon squeaks. But the balloon experiment is a simple demonstration, capable of just a few annoying noises. Your body is a highly-developed machine. You can make noises a lot more impressive than any balloon.
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