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equivalent pressure 1

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midsidenode

Mining
Sep 18, 2006
85
I am not well versed in acoustics so bear with me......
I am reading a report that presents an acoustic noise chart whereby a range of 1/3 octave sound pressure vs a frequency range is plotted. The report states a "worst case" value (dB) at a specific frequency and goes on to say that this can be converted to an equivalent 3-sigma pressure. I am familiar with using Miner's rule to convert to an equivalent 3-sigma peak load factor (G's) using a PSD curve, natural frequency and structural gain, but not familiar with converting acoustical noise into a pressure. Can someone explain this to me?

v/r,
msn
 
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SPL = Pref*10^(dB/20)

Pref for atmospheric sound is 2e-5 Pa. Quick check 1Pa=94 dB, ok

The 20 is in there rather than 10 because energy is proportional to pressure^2

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
Thank you Greg.
I am reading this report and it says that 144.6 dB at 400 Hz converts to an equivalent 3-sigma pressure of 2.11 psi. That doesn't seem correct. Thoughts?

v/r,
msn
 
Taken literally, that's almost certainly wrong. 2 psi is phenomenally loud. So they must mean something else. This is in air?


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
Yes - it's indeed air and a very violent environment. The overall sound pressure level (OASPL) for the frequency spectrum is 164.2 dB. How is the OASPL value calculated using the data of the frequency spectrum?
thanks Greg.
 
Doesn't sound ;-) totally implausible; if you're standing next to the Tower of Power speaker stack, you can certainly feel the pressure changes from the speakers impacting on your skin.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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