More explanation of a very interesting phrase

[stephaneeybert]

I read your phrase "A given piece of music focuses on certain pitches and ignores others, determined by the key of the piece." and as a newbie in music wondered what exactly it means. How to translate that in simple arithmetic ?

[ryukinix]

@stephaneeybert take a read on that: https://en.wikipedia.org/wiki/Musical_temperament.

I'm sure will clarify, but a summary: music, in general, don't use all the possible frequencies, it uses a discrete set of "valid" frequencies dependent of the temperament system. Modern music you could assume that the system used is equal temperament system.