Q:

How we hear sound computer vs human experiment -amplitude and volume-Interesting

Suppose everything I will say from now on:
We open song-A from youtube(1 computer) in 5 tabs(5 same songs started same time) with same volume.By intrigue and test it will act like same song only played as once with same volume.The volume is not multiplied with 5 times.
In real life think there is 5 identical singers named B(think as copies).They start to sing song-A at the same time with same volume from same location(Think like they are dots binded together so their distance is the same to listener).My intrigue and knowledge says we would hear 5x the amplitude of Song-A so by the fraction of logarithm the sound we hear and our ear processed will increase differently then the computer example.
My dilemma is how computer sends 5 song-A to speaker but give same volume as one as different in second example.It might be a thing that is not often thought by people.Can someone explain the mechanism?

A:

I think people have misunderstood that this is a hypothetical question.
Anyway, in short, playing two sound sources simultaneously on your computer will add them together (double the power / +3dB, etc). This can be observed by having multiple mono tracks in a DAW, using your computers motherboard output if necessary, muting all tracks and progressively un-muting. The thing with a computer output is that it has controllable amplitude. So whilst you may be combining the audio signals, your overall output amplitude will be capped, which will simply result in distorted audio when you've 'added' too many signals. As @Andy aka mentioned above, some computer soundcards will mix/limit audio output so that it doesn't distort.
In the real world, such an amplification cap does not exist. Whilst, as @Richard Crowley mentioned in his answer, addition / combination of sound waves in air is incredibly complex, in theory if you were able to keep creating multiple identical sounds from the exact same source location they would continue to 'add' together.

