system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it louder when a bunch of people make the same sound at the same time?

For example, a stadium full of people singing the national anthem is louder than one person singing the national anthem, but they're each individually singing at the same volume.
gpt
Waves interfere constructively and destructively. Think about pushing someone on a swing, when you push them the way they are already swinging they swing higher, and when you push against their motion they swing less.

Waves that encounter each other then will combine into one wave. The peaks of the sound wave from one person will combine with the peaks of other people's voices to push the combined sound louder.