Sound Science Completed Craft

Sound science


Gibbons, frogs, and some other types of animals develop a big bulge, or sac, in their throat when they call. These balloon-like body parts help make their call louder. Why? By pushing a lot of air into the sac, the air molecules get crowded closer together, which makes the sound louder. Try it yourself!


Boy with balloon

What you need

2 balloons

Listening to balloon


Blow up one balloon and tie it closed. Hold the balloon up to your ear. Use one finger to tap on the side of the balloon at your ear. Can you hear that it makes a louder sound?


Talking at balloon


Put your mouth up to the side of the balloon and talk in a normal voice. The balloon will make your voice sound louder. Try this! Blow up one of the other balloons, but make it bigger or smaller than the first balloon. Try tapping your finger against the balloon again. Does having more or less air in the balloon make the sound louder or softer?