1What a sound really is
A sound is a wave, and waves can add up
You only need two ideas. Watch each one:
A sound is a wiggle
A sound makes the air pressure rise and fall, over and over. Drawn out, it looks like a wave: peaks (a push) and dips (a pull). A louder sound makes taller peaks.
Waves add point by point
When two waves meet, your ear hears them stacked. At every spot, add the two heights together: push + push climbs higher, but push + pull can cancel to zero.
2Two ways the waves can line up
Peaks on peaks vs peaks on dips
Both waves are the same size. The only thing that changes is where the second one sits next to the first:
The "add up" lineup
Both push at the same moment, so the heights stack into one taller wave — twice the pressure-wave height.
The "cancel out" lineup
One pushes while the other pulls at the same moment, so the heights erase each other — flat and quiet.
3Your turn — slide the second speaker
Drag the lineup and watch the two waves stack
The teal wave stays put. Slide the coral wave left and right and watch the purple wave — that's what your ear actually hears when you add them together.
4Now change the size of one wave
Can a smaller wave cancel a bigger one?
The practice waves had equal heights. In this new test, the coral wave is only half as tall as the teal wave. They still have the same pitch. Predict what happens when their peaks and dips meet.
Guess before you push it
The teal wave has height 2 and the coral wave has height 1. When we slide them exactly opposite, what will the combined wave look like?