system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does software volume control works?

I have noticed that for example in windows volume of 32 and youtube 100%, is quieter than 34 and 85%. Multiplying them would suggest it to be 29.

Also, the jump from one level to another might feel much bigger than what it was, eg: jumping from 38 to 40 would be a 5% increase, but it feels much more.

I have noticed that this phenomenon is quite universal, with software-controlled volume.

This leads me to believe it is not having a linear relationship but something more complicated.
gpt
Human hearing means that for something to be heard as twice as loud it has to have roughly ten times the power.  Volume scales that are marked out from 0 to 100 take this into account so that maybe every 20 units on the scale mean ten times more power.  If a volume of 60 means 1&#8239;W of power then 80 means 10&#8239;W, 100 means 100&#8239;W and 40 means 0.1&#8239;W.  Also, on this scale of 20 units for a factor of 10, going up 6 units is a factor of 2, so a setting of 66 would mean 2&#8239;W.

The details of how these scales work will vary with different software but they'll generally use the same principle: going up the same number of units means *multiplying* the power by some amount.  You talk about going from 38 to 40 which might increase the power by, say, 26%.  Going from 40 to 42 would increase it by the same percentage and the same for anywhere on the scale.  Going from 98 to 100 would also increase the power by 26%.  In mathematical terms it's a logarithmic scale.