[linux-audio-user] measuring sound volume

Steve Harris S.W.Harris at ecs.soton.ac.uk
Tue Mar 16 10:15:31 EST 2004

On Tue, Mar 16, 2004 at 11:54:49 +0900, Patrick Shirkey wrote:
> I have been asked to work on a large outdoor party again this year.
> This time we are going to have multiple zones with powerful equipment.
> Can anyone give me some tips on appropriate spacing to enable a good mix 
> of cleaness and sound fusion?
> For example if I have 4 x 20KW systems how far apart from each other 
> should they be so they don't overpower each other?

I dont know how much SPL you get from the equipment, but if you are Xm
from one speaker and X*2m from the other, the nearest one will only be
about 12dB louder.

the inverse square power law gives
difference = (distance from A / distance from B)^2

in dB's 20 * log10(difference);

so to get 40dB's of difference (seems like a reasonable minimum) you have
to be 10x nearer to the nearest stack than the next nearest.

How loud those dB's appear to be depends on what the SPL is, I think you
need more difference with a higher SPL, human ears compress, especially at
high volumes.

Hope that helps,

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