system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do multiple similar sounds put together become louder? Example: An audience clapping.

Do the sound waves build up with each other somehow? Thank you!
gpt
You can look at sound like water for this case, if you wave your hand at the surface the displacement from your hand will make a wave that gets smaller as it travels, now if you wave your other hand right underneath it in the same manner it will build it up again, if you do another wave at the opposite direction of the first, the turbulence will be destructive and both waves will cancel each other.

In the case of people cheering they are all doing the same sound more or less so they are building it up.

Noise canceling headphones use the opposite thing, they will make destructive turbulence that cancels the ambient noise.