also, intervals and their function collapse at certain tessitura levels. either collapse or completely change. eg. a super high b9 on top of a maj7 chord actually sounds good. it is the 5th higher than the lydian b5. it "shouldnt" work but it does. the intervallic relationship is different, spread higher. the b9 dissonance between tonic and b9 is not present.
similarly, if i put the tonic ABOVE the maj7 in a maj7 chord, it sounds horrible because of the interference pattern that ensues.
thus tessitura and intervallic function are interlinked.
octave displacement of intervals matter.