Why is a 100 person choir singing the same song not 100 times louder than one person?

Question

I suspect it’s something to do with sounds waves so have flaired as physics, but not sure?

In: 896

Answer 1

Perceived loudness and signal power aren’t 1 to 1

If you have 100 singers in perfect unison then there’s 100x as much sound energy and the changes in the air pressure(up and down) will be 10 times greater. This greater change in air pressure results in more movement of your ear drum

But when your ear drum passes the signal to the tiny hairs and the hairs to the nerves your brain scales things down a bit. A 10x increase in the air pressure swings results in a 20 dB increase, but so that you can hear both rustling grass and deal with the roar of a lion your brain consolidates loudness ranges so each 10 dB increase sounds twice as loud so the 100x singers sound about 4x as loud as a single one would at the same distance.