At the risk of evoking (good word for the thread) a deluge from the knowledgeable:

I have seen treaties on why a particular key is sadder or melancholic comapared to (say) C (major). The true-temper scales (aka piano notes) are cited because the octave is 8 notes compromised as a subset of what (on say a guitar) would be 12 notes spaced (as a frequency) consequetively by the twelfth root of 2.

But then I is a drummer and wud not no abart such fings. But as an Electronic Engineer..................