[al2o3cr]

    Technically speaking this is all "distortion" of the original signal.

Not really - if it was "distortion" you could MEASURE it with an oscilloscope. There's another, less polite, word for most of those comparisons.

[TheOtherHobbes]

If you want to measure it, an oscilloscope is the wrong tool.

You can see it - very clearly - using a lab-quality audio signal analyser from a company like Audio Precision.

https://www.ap.com/

And a popular way to model it is with a DSP technique called a Volterra series.

You may want to consider that impolite words are also used about people who consider themselves very knowledgeable about domains where they show no evidence of understanding the fundamentals.