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A-Weight correction for flat noise spectrum

Question asked by mgallant on Jul 29, 2013
Latest reply on Aug 2, 2013 by mgallant

I perform audio noise measurements using a very high high-quality slow noise ound card and 24bit/96kHz sampling rate. I wrote a low-level application to sample and compute the RMS noise using this approach. The effective "noise bandwidth" is ~ 46 kHz (measured) using this approach.

These noise measurements are not weighted. 

My question is ASSUMING A UNIFORM FLAT NOISE SPECTRAL DENSITY up to 20 kHz, I calculate (integrating the functional form for the A-Weight transfer function)  that compared to a unweighted value (for a 20kHz noise bandwidth), the A-weighted value is almost exactly 2.0 dB lower. If this correct?  I read an EDN article stating the difference was 2.5dB.

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