Noise Rating Curves
Noise Rating Curves
(OP)
I need some explanation as to what is meant by NRC (Noise Rating Curves). I have a Spec on Noise criteria, and I have two values: dB(A) and NRC. NRC is lower. How are they related?
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RE: Noise Rating Curves
Is it possible that's what it means here?
Kinda hard to help you though if you don't even know what "dB(A)" means.
RE: Noise Rating Curves
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
RE: Noise Rating Curves
RE: Noise Rating Curves
Noise Rating (NR) is common in Europe.
For NR curves, see http://ww
Their relation will depend on the spectrum shape.
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Syl.
RE: Noise Rating Curves
One exercise I tried was correcting an NC curve to a dBA octave band spectrum and summing octave band levels. The calculated dBA was not in the range of the charted NC-dBA numbers.
One site I found indicated the relationship between NRC and dBA can vary from 0 to +11. Sounds meaningless. Having a clear relationship, that is.
Ted
RE: Noise Rating Curves
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
RE: Noise Rating Curves
I went back to my calculations and found an error. I recalculated the equivalent dBA of the NC-70 curve to be 77dBA. Seems in line with referenced charts showing NC and equivalent dBA.
Is it fair to conclude then that there is a relationship of NC value and equivalent dBA? Correct the NC octave levels to A-weighted octave levels and sum the resulting A-weighted octave levels to calculate the equivalent dBA.
Ted
RE: Noise Rating Curves
My favourite was the Composite Rating of Acoustic Preference. Not a good acronym though.
- Steve
RE: Noise Rating Curves
I'd steer clear from trying to document and use a relationship between dBA & NC (or NR). Quite honestly, they are meant for different things, and it's possible that by stating one, you'll miss something.
You are correct that by summing the maximum NC levels you'll end up with a dBA value, but by no means does this imply that, if you are below a certain dBA level, you automatically meet a given NC value.
If the criteria requires NC levels, specify a NC value. If the criteria is a dBA level, specify a dBA level. Realize that both have limitations.
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Syl.