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Old   March 13, 2018, 04:00
Default sound pressure level
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Hi,
I am interested how to calculate SPL (sound pressure level) in CFX. There is one formula in help (SPL=10log(P'/Pref)) but I don't know how to calculate P' which is pressure fluctuation relative to the background pressure. Pref is constant (10^-5 Pa) and is called reference pressure level.
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Old   March 21, 2018, 12:41
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The formula I found is SPL = 20log(P'/Pref)
Pref is 2*10^-5 [Pa]

I don't know why your formula is different, but I've researched and checked mine: 194 dB is the loudest possible sound @ 1 atm.
I see, yours should be 10log(P'^2 / Pref^2).
I've seen both values for Pref now, so who knows. It is a 6dB difference using the two values.

P' is the amplitude of your pressure waves; not the peak to peak amplitude, just one side.

You would have to look at the pressure at some point over a time period and graph it transiently to get the amplitude of the pressure waves. Or just look at the maximum pressure above the average pressure to get your amplitude.

Last edited by evcelica; March 21, 2018 at 16:03.
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