Very complicated question
In a way 'yes', but not A scale, as in one
Take any sheet of classical-music, and you will be able to read out the key and scale, in top of the sheet. -So done?
No, because if you then look at the actual notes, you will see symbols that 'moves' either all notes of a semitone out of the given scale, or single selected notes, inside the actual score.
Symbol # sharp means played one semitone higher
Symbol b flat means played one semitone lower
So those semitones, are they out of scale?
Yes,
the scale. They are out of
the scale denoted in the top of the sheet, but not out of
A scale, as in
another scale!
What the composer does, is to change the denoted scale to a
different scale, for just
that chord!
Notes played simultaneous 'must' create a harmony (if you arent making disharmonics for horror effect or such). Notes in A scale are harmonic. So when notes are played +1 or -1 semitone, they are together with the other notes, in a new scale, and a new harmony is created. Being able to chage scales and keys and build pleasant harmonics, as a
whole is what clever composers can do.
