We can’t see a dust mite but we know they exist.
And the same is true for sound and electrical waves. We cannot see them with our eyes but, through our equipment, we can generate a visual representation.
That representation is not the real deal, but rather a translation or interpretation molded to fit our limited senses.
What this means is that we build our systems around invisible forces and then manipulate them for best results through mental constructs built around less than perfect (and certainly incomplete) translations of real events.
It’s a leap of faith that the constructs we rely upon to make decisions are correct.
We don’t really see if using an optical cable vs. a coaxial one is better or worse. Using our measuring equipment we can get an incomplete glimpse of the results, but those results are only one view of the invisible.
We can also use our ears to test the validity of our theories as to what works and what doesn’t.
Either method of observing that which we cannot see has its pluses and minuses.
If I can hear it I don’t need to see it.