...Is there a physics reason as to why we are unable to locate the origin of these frequencies? I suspect it has something to do with the long wavelengths, the relatively close spacing of our ears ...
Bingo.
From what I understand we can triangulate the direction of sound based on the different arrival times of the waves from 1 ear to the other. Under 100Hz the length of the sound wave gets too long for our ears to tell apart. Grade 12 Physics was a looong time ago for me, but a principle of imaging is that you cannot see an object which is smaller than the wavelength of the wave with which you view it.
In other words, if the wavelength of the sound is greater than the size of the... driver?, you can't image where it is.
I think.
snazzed
EDIT: The above is wrong... it just doesn't compute. But it does have something to do with the length of sound waves under 100Hz. I guess it was just *too* long ago.
