KaiserSoze
Addicted to Fun and Learning
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Well, Linkwitz has written the following to which I agree.
Take into account the equal loudness contour and then you'll find that for the 2nd harmonic of for instance 20Hz where it falls is 40Hz and our ear is more sensitive there. So much more sensitive that for a 90dB SPL 20Hz tone, if the 2nd HD is 10% that is 70dB SPL our ear hears it at the same volume as the fundamental. And if the 2nd HD is higher than 10% for 20Hz we hear the 2nd HD as louder than the fundamental.
For the 3rd harmonic it is even worse, a 90dB SPL 20Hz tone can only have 3% 3rd HD before the 3rd harmonic becomes louder to the ear than the 20Hz fundamental.
Our ears/brain can do a trick though, they can fill in the missing fundamental in such a case. But don't think you're actually hearing good deep bass under the crazy distortion figures most 2-way speakers measure. You're not.
https://en.wikipedia.org/wiki/Equal-loudness_contour
So yes, agreed that the prevailing opinion on not being able to hear those crazy HD figures in the bass is complete bs. (also from personal experience)
I thought I had read most of what Linkwitz provided about speaker design, on his site, but I don't recall seeing this. And it is an angle that had not occurred to me, even though it seems obvious once made aware of it. To say it succinctly, since our hearing is more sensitive at the harmonics of a deep bass note than at the deep bass note itself (the fundamental), harmonic distortion does not have to be especially great in order for the distortion to sound louder to us than the fundamental.