I stumbled upon the word/phrase on Wikipedia while reading about Modes. Link (Mode (music) - Wikipedia)).
Part 1:
"Since Dorian mode is the “middle” mode, we compare it with other modes:
(♯ and ♭ are dual, 2 and 7 are dual, 3 and 6 are dual, 4 and 5 are dual)
Dorian is self-dual, Mixolydian mode and Aeolian mode are dual, Ionian mode and Phrygian mode are dual, etc."
Part 2:
"Aeolian dominant scale (Dorian ♯3 ♭6 scale) can be called “anti-Dorian scale”, since it and Dorian scale are the only two scales which are self-dual.
Dual triads:
major triad ~ minor triad
diminished triad (self-dual)
augmented triad (self-dual)
Dual seventh chords:
major seventh chord (self-dual)
minor seventh chord (self-dual)
dominant seventh chord ~ half-diminished seventh chord
diminished seventh chord (self-dual)
augmented major seventh chord ~ minor major seventh chord
Dual keys:
D (self-dual)
A ~ G
E ~ C
B ~ F
F♯ ~ B♭
C♯ ~ E♭
G♯ ~ A♭ (the same key, self-dual)
D♯ ~ D♭
A♯ ~ G♭
E♯ ~ C♭
B♯ ~ F♭"
I don't understand what they mean by a scale being "dual" with another scale, or "self-dual".
Does anyone knowledgeable want to enlighten me? Thanks.
Submitted June 02, 2024 at 01:24PM by Hot_Sport_7827 https://www.reddit.com/r/Learnmusic/comments/1d6h1gi/what_does_it_mean_when_a_scale_is_dual_with/?utm_source=ifttt