I looked further into the Isolda, pictures and the dimension estimates I made. I expect that 6.6uH is quite wrong, but that 0.002uH is quite wrong too (for 2 meters).
Given the lack of consistent numbers for Isolda, could be a function of the cheap meter, or measurement error, let's use the Isolda as a reference, use some of the inductance numbers in the chart, and the shown (but wrong) speaker simulator, using inductance only.
My Calcs Value on Graph
ISOLDA 2.6 2.6 (Used as ref)
That's close enough to me, to show that inductance alone completely explains Chart 3, certainly within the framework of the obvious measurement errors.
Here is what you have done:
1) Showed a graph with expected change in frequency
2) Showed that order of magnitude characteristic impedance had a rough correlation to the measured results.
What you did not do:
a) Investigate other related effects ... like INDUCTANCE.b) Show a direct correlation via a measurement of impedance and measured error
c) Show a mathematical correlation between impedance and measured error.
See, I just did #3 above, and showed a very close correlation between inductance and the measured results. That's science.
You also left out many necessary details so that your experiment could be corroborated.
And ...perhaps most of all, you did not relate your result to what the actual change in frequency response is.
On the very worst cable it is 0.4db at 20KHz.