Two points that (as usual) were overlooked. First, I clearly stated "approximated".
No, you said and I quote: "A-weighting approximates an inverse of the Fletcher-Munson curves." Curves? How can one filter curve in the meter approximate all of those curves? And further, as I said, the db error with 40 phon alone is 10 db. Since these are power ratios, every 3 dB corresponds to doubling of power. 10 db is 8X difference in power.
So there approximations and there are approximations. Here is the wiki again on this topic:
The curves were originally defined for use at different average sound levels, but A-weighting, though originally intended only for the measurement of low-level sounds (around 40 phon), is now commonly used for the measurement of environmental noise and industrial noise, as well as when assessing potential hearing damage and other noise health effects at all sound levels; indeed, the use of A-frequency-weighting is now mandated for all these measurements, although it is badly suited for these purposes, being only applicable to low levels so that it tends to devalue the effects of low frequency noise in particular.[1] It is also used when measuring low-level noise in audio equipment, especially in the U.S.A.[citation needed] In Britain, Europe and many other parts of the world, broadcasters and audio engineers[who?] more often use the ITU-R 468 noise weighting, which was developed in the 1960s based on research by the BBC and other organizations. This research showed that our ears respond differently to random noise, and the equal-loudness curves on which the A, B and C weightings were based are really only valid for pure single tones.[citation needed]
Exactly the same points I have been making. When a measurement has such gross errors, you don't get a free pass by saying "well, I said approximately." This, when I gave the correct explanation. Not once. But twice. I even linked you to my article. Yet here you come again???
Second, the posts I reported made a big deal out of using the Fletcher-Munson curves, including using up a large part of the page with their graphic representation.
Yes, as *curves* with the threshold being key. Not as one dumb number your uncalibrated SPL meter spits out. You perform an FFT of the noise in your room and then compare the two spans together as I showed:
You see the solid line saying "threshold?" That is Fletcher-Munson. The dashed lines are computed conversion of the noise to corresponding sine power (ERB) and plotted against that.
Now you can easily compare the two. Where your measurement falls below the solid line of Fletcher-Munson threshold, to the average population it would be inaudible
at those frequencies. If above, the reverse. No single number on your meter may apply.
One particular person's posts continue to be arrogant, authoritative in tone, and often incorrect. It is reminiscent of another member who no longer participates here (first name initial E).
And I think amirm still owes PeterA a public apology.
Right now I am looking for your apology in accusing me of not knowing what A-weighting is. And for continuing to throw terms and misinformation out there that you have not researched in the slightest.
