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 pushes the air up, then down, 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 as loud.
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 push it all the way to opposite
Slide it until every peak sits on a dip 🤫
Both waves are still playing — nobody turned anything down. You're only moving the second wave so its peaks land exactly on the first wave's dips. Guess what your ear hears first, then push it there and listen.
Guess before you push it
You shift the second wave until its peaks sit on the first wave's dips. Both speakers are still playing at full blast. Does the sound get louder, or vanish?