Why the obsession with the lowest octave


From what is written in these forums and elsewhere see the following for instance.

Scroll down to the chart showing the even lowest instruments in this example recording rolling off very steeply at 40 Hz.

http://www.homerecordingconnection.com/news.php?action=view_story&id=154

It would appear that there is really very little to be heard between 20 and 40 Hz. Yet having true "full range" speakers is often the test of a great speaker. Does anyone beside me think that there is little to be gained by stretching the speakers bass performance below 30-40 cycles?
My own speakers make no apologies for going down to only 28 Hz and they are big floor standers JM Lab Electra 936s.
mechans
Dan_ed... I don't believe that you can call modulation below the fundamental a "harmonic".

Consider a violin string. It is fixed at each end. and sounds a fundamental tone. But, by soft placement of a finger in the middle of the string you can immobilize that point of the string so that each section (end-to-middle and middle-to-other-end vibrate at a higher frequency because the length of sting is shorter. I don't see any way to make the string vibrate at a lower frequency (other than by loosening it up).
Mixing two different tones is another story but the lowest frequency is called root and the rest are overtones that are higher. When you play instrument with complex harmonic structure (typical for percussion instruments) like piano - each key produces tone and overtones. There is no sub-overtones. The same is with guitar and many other instruments. Some things like bells produce subharmonics but for the rest of the instruments it is not common. You can obtain subharmonics with violins using special techniques (not very common) but you won't get it from the piano's individual keys.
i relate to what ecruz said.

the first time i hooked up subs it totally baffled me how the soundstage expanded.

also the perception of low level detail.
I have OHM 5 series 3 near full range floorstanders that do well down into the 20-30hz range and Dynaudio Contour 1.3mkII monitors that I would estimate do well into the 40-50 hz range on the same system.

That extra low end makes a big difference on most everything play!

I had the monitors first to see if I really needed the low end I knew was not there. I do to be totally satisified, though the Dyns do a ver satisfying job with the low end UNTIL you compare with the others that plunge the depths way better by design.
Thanks for the correction, Eldartford and Kihanki! I am mixing myself up. The fundamental IS the lowest sinusoid. I'm sounding like Irwin Corey again. ;-)