Noise Levels

[Daddy Cool]

Can anyone help or point me in the right direction?

i need to provide a noise level (in dba) for several condensing units of different noise levels.

i know it's not as easy as adding them all together, and that it's something to do with logarithams, but don't have any formula or simple calculator to do it for me.

Any assistance greatfully received.

[Brian_UK]

Daddy, have a look at this:-
http://www.nohsc.gov.au/OHSInformati.../NOISECONT.HTM
and see the paragraph on 'adding levels together', it may help...

[Argus]

Here?s another similar site that contains a basic rule of thumb addition table about halfway down.
http://www.ccohs.ca/oshanswers/phys_...ise_basic.html

But you need to know what you are adding, whether it is sound power or sound pressure.

If you are trying to predict sound from more than one source at a given distance, the surroundings and ambient noise will have an effect.

You are right ? the maths can be horrendous. There are professional acousticians available.
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[Daddy Cool]

Thanks Chaps that should be enough to give a reasonable idea.

[botrous]

Guys , just give 2 days to give u full formulaire for the noise calculation , i have just to put it together . if anyone interrested please say so ........

[Daddy Cool]

Botrous, we look forward to it. i did get a formula, but it was vast. i used to have one where i used to work, it was in ms excel and really easy to use. mainly used it for chillers when customers asked how they compared, data from one company was at 10 metres the other at 3 metres and so on.