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A speaker squeezes the air. Watch the squeezes march across the stage.
Sound Waves lab · Last updated: 16 October 2026
A loudspeaker pushes and pulls on the air in front of it. In this lab you can see the air squeezed together and spread apart, and watch those squeezes travel across the stage. Sound stops being invisible.
What you'll discover
- Sound is a wave of squeezes and stretches travelling through the air.
- The air itself only jiggles back and forth; the pattern is what travels.
- Faster vibrations give a higher pitch, and bigger squeezes give a louder sound.
The science in plain words
Every sound starts with something vibrating: a guitar string, your vocal cords or the cone of a speaker. When the speaker cone moves forward, it squashes the air in front of it into a region of higher pressure called a compression. When it moves back, it leaves a region of lower pressure called a rarefaction.
Each squashed layer of air pushes on the next layer, which pushes on the next, so the compressions travel outwards. The air molecules themselves only shuffle back and forth a tiny distance. This kind of wave, where the jiggling is along the direction the wave travels, is called a longitudinal wave.
The number of compressions each second is the frequency, measured in hertz, and we hear it as pitch. Humans can hear roughly from 20 to 20,000 hertz. How strongly the air is squeezed is the amplitude, which we hear as loudness.
In air, sound travels at about 343 metres per second at room temperature. It needs something to travel through, so it cannot cross empty space. That is why space is silent, despite what films suggest.
Where it fits
- India, NCERT: Class 9 science, Chapter 11: Sound
- United States: Grades 6 to 8
- Next Generation Science Standards: MS-PS4-1
Common questions
How does sound travel through air?
A vibrating object pushes air molecules together and pulls them apart, making compressions and rarefactions. Each layer pushes the next, so the pattern travels outwards to your ear.
Can sound travel in space?
No. Sound needs a material such as air, water or rock to travel through. Space is almost empty, so there is nothing to carry the vibrations.
What makes a sound high or low?
The frequency, or how many vibrations happen each second. More vibrations each second give a higher pitch; fewer give a lower pitch.
Related labs
- Wave Motion: Shake one end of a cord. How fast does the wave run, and how long is each wave?
- Doppler Effect: A moving dipper squashes its ripples in front and stretches them behind.
- Beat Frequency: Two nearly equal notes together go loud, soft, loud, soft. How fast is the wobble?
See all physics labs or every Taz science lab.
Try it yourself
The Sound Waves lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.