system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does a large crowd of people singing in unison never sound dissonant while there are loud individuals in that crowd that do?

This question hits me every time I'm at a concert. If I listen to the crowd as a whole, the singing sounds perfectly on pitch. But if I listen to someone standing next to me, it can sound terrible if they are just totally off. Are there that many good singers in every crowd?
gpt
Your brain is doing a few tricks with the sound. Keep in mind, only one ear drum per ear, and it's only capable of doing so much.

So, when you have several people singing, odds are they are getting close enough to the actual notes. They are going to be up and down from that note, but especially in a well known song, close enough is good enough in a group. What will happen is the varying vocal qualities of the group are going to wind up harmonizing with each other, due to resonance.  Notes are very rarely so pure that they hit it *just* so. In fact, many very gifted singers have a timbre to their voices which is naturally resonant. You get overtones that are not pure, and give the sound a lot of depth. In a large crowd, this is going to get exaggerated, because you in essence have one enormous voice with all the little crinkly bits around the edge to give it character.

Go listen to a large professional choir to see the difference. When you get very precise technical singers together, they don't resonate the same way.