I suspect it’s something to do with sounds waves so have flaired as physics, but not sure?
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Decibels work at a logarithmic scale, meaning that you need to double the power to get just slightly more dB
Sound functions on a logarithmic scale. Meaning it takes a 10 times increase in intensity/power to be heard as twice as loud. 100 people is not enough to produce the amount of power (energy) needed to reach a 100 fold increase in loudness.
If you turn on 100 lightbulbs, it’s 100x brighter than one because they’re all producing their own light, all those beams of light combine to be more powerful. 100 people all producing sound waves are doing pretty much the same but because sound is just vibrations in the air, they tend to sync up or overlap, it’s the difference between putting 100 small stones on a scale and seeing the weight increase by 100, and throwing 100 stones into a pond and watching the ripples overlap and cancel each other out
So many wrong answers. Everybody saying sound is perceived on a logarithmic scale is right.
Because the singers are not synchronized on a fine scale and not spaced out taking the wavelength into account. At a given moment in time some of their sound interferes destructively and cancels out. Doubling random, weakly correlated sounds adds 3 dB to the power. So you would get about 20 dB increase from 1 to 100.
Human hearing is also non-linear, and adapts to louder noises by becoming less sensitive. In practice it is not that important to tell 99 and 100 sources of sound apart. You just need to know there is “a lot”. An increase of 8 to 10 dB is perceived to be twice as loud.
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.
I think folks are missing the point in their answers. A 100 person choir does, in fact, produce 100 times the vibrations as a 1 person choir. However, the human brain perceives this energy on a logarithmic scale. That allows us to hear a quiet whisper and a loud gun shot, which are many orders of magnitude different in the amount of air vibration.
I was just going to say that decibels don’t stack in a linear fashion but some people here explained it 1000x better and now I feel dumb. Thank you
Humans can’t detect small variations in some forms of energy, and instead we interpret these things differently than physics would. Sound is one of these. Instead of hearing a soundwave with twice as much energy as twice as loud, we hear it something like .3 (the result of log10(2)) times as loud (the actual value may be from a different log base in practice, but the scale is similar enough). This is far more useful to us, because now we can hear small sounds (like an animal walking in a forest) while not instantly being deafened by loud sounds (like an animal roaring to scare away predators).
There is also a potential of the energy being less based on distance (sound becomes less energetic at a cube rate of distance from the source), but that is the lesser influence in a single venue. It is also possible to have constructive/destructive soundwaves, but the chaos of a choir arrangement is not precise enough to cancel out the energy involved at any real rate in either direction; that is something more often seen with precisely placed and timed electronic systems.
2x the power input= only 3db increase in sound level output.
so if 50 people could pump out 40db. 100 people only push it to 43 db.
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