The Speaker Cable

[Steve Mac]

2 kHz (give or take) is where human hearing peaks (most efficient), so wide BW distortion must be below the signal's noise floor around/at this frequency.

The higher the signal impedance, the higher the speaker's effective impedance, ergo the higher its system Qt.

GM

It's true that the largest component is 2KHz.
But just to make it more clear or more muddy....

A Square Wave = The sum of odd harmonics of a sine wave where the amplitude of each is 1/n where `n' is the harmonic number. Now take "n" to infinity and you have a perfect square wave.

First a square wave is theoretically impossible in a constrained frequency domain.

So for a 2KHz square wave with amplitude of "1V" for argument's sake:
A 2KHz square wave =
1V-2KHz sine wave + 0.3V-6KHz sine wave + 0.2V-10KHz sine wave +
0.142857V-14KHz sine wave + 0.111111V-18KHz sine wave + 0.090909V-22KHz sine wave
+ etc,etc. ad infinitum....

...but we're only interested in getting the highest reproducible frequency unadulterated
...to the speakers.
...and the blips in the example appear to be in the "audible" range at significant amplitude
...to hear.

I'm not really drawing any conclusions....and thanks GM for the primer links...
It's just that I'm glad I took calculus based physics in college.