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question on using my SPL meter

I've got a new toy, a Phonic PAA2 Audio Assistant that has an SPL meter with a 31 band spectrum analyzer. The manual tells how to operate it but doesn't offer much in the way of practical advice. From what I can gather from looking around the web I should be using pink noise, but I'm not sure about the weighting. It will let me use flat, A, or C.

I found the info below on one site but I found others that say to always use A. Any idea which is correct.

"For the most part, "A" weighting is used for relatively low level SPLs in the range of 20 to 55 dB and it's response curve correlates most closely to the ear's frequency response at these low listening levels. "B" is used for measuring moderate SPLs between 55 and 85 dB and the "C" weighting network is used for measuring SPLs of 85 dB or more. "
herman
4 responses Add your response
jeffreybehr's avatar
jeffreybehr
805 posts
 
Use the metering weighting that was used to create the pink noise. If the pink noise isn't labled as C-weighted, it's not weighted and you should use the meter's 'flat' position. Mismatching weighting v. no weighting will give you VERY inaccurate results. Does the system generate its own pink noise or do you have to use, say, a recording?
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hrcapers
65 posts
 
Use the C weighting and pink noise. I'd also test with at least 85 dB just to drown out any ambient noise.
eldartford
4,262 posts
 
Your quote indicates that there is no "right" answer. The ear's variable frequency response as a function of SPL is why preamps used to have "Loudness" controls. Nowadays you have to play with the tone controls, but they have become rare in modern preamps, if not completely extinct. This is "progress"?
jeffreybehr's avatar
jeffreybehr
805 posts
 
I repeat--use the metering-weighting system same as the noise-weighting system. Mismatching them creates LARGE errors at the frequency extremes.

C-weighting should be used with 'flat' (ie unweighted) noise only if C and A are the only choices. In that case, it's the lesser of 2 evils...but it's still WRONG.
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