chessrock said:
Since this thread has taken a rather interesting and unexpectedly education turn ... I was wondering if any of you has any insight as to why distortion can sound harsh to our ears if it's in the higher frequencies ... yet oftentimes pleasing if it's in the midrange and lower frequencies (?)
What is it, about the distortion, that causes the sensation of "pain" or fatigue to our ears ... and why is it so pronounced at higher versus lower frequences? I'd be interested in the theories.
There's a paper by Russell A. Hamm about different distortions that should be easy to find with Google. But here's my thoughts on it. I'll use an A chord as an example, since that requires the least math to understand it:
An A Major chord consists of 3 notes: A (the root), C# (the third), and E (the fifth).
This A chord will start with A=440Hz, we can build the rest of the chord from there:
A =440.00
C#=554.37
E =659.26
Ok, now imagine that someone is playing the A note and clipping it badly, so you're getting a lot of 3rd and 5th harmonic distortion. Those distortions are electronically creating and are perfect 3 and 5 time multiples of the original A note. That works out to 3x440Hz=1320Hz, and 5x440Hz=2200Hz.
But remember, we live in a "tempered" world, so the 3rd and 5th note of a "real" A chord are tuned to be pleasing to the ear. So what "real notes" happen to be near those two electronic distortion frequencies?
The octave of our "tempered" E note (the 5th of the original chord) is 1318.51Hz, clashing with our electronic distortion 3rd of 1320Hz.
The second octave of our "tempered" C# note (the 3rd of our A chord) is 2217.46Hz, a pretty fair distance from our electronic 2200Hz distortion (the fifth).
In simple terms, these electronic-generated distortion 3rd and 5th harmonic notes conflict with our tempered notes and create the "uglys" that we hear.
Even order harmonics (the second and the fourth) are simply octaves of the original notes, and just contribute to the fatness of the sound - they're in perfect tune with the originals.
Does that help explain it any better?