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When laying out the notes in the two-dimensional Wicki-Hayden layout, which is the most symmetrical layout I know of, it is visually clear that D is the "most central" note.

Why, then, doesn't D play a central role in music theory? Or does it? And similarly for the related Dorian scale.

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6 Answers 6

D's central position in Wicky-Hayden layout is an artifact of the fact that Dorian mode is a symmetric scale (its descending interval pattern and ascending interval pattern are the same) in some tunings, including the twelve tone equal temperament (and it's the only such diatonic mode).

Even though I'm sure this mathematical property of Dorian mode has been exploited by some musicians, I'm not sure whether it has any real psycho-acoustic importance. Not all mathematical properties have psychological consequences.

In this case, Western musical tradition does not seem to care about this symmetry as much as it cares about the fact that I-IV-V triads create a major (Ionian) scale (another mathematical property).

Besides, this symmetry does not exist in just intonation (with its greater and lesser whole tones, between C-D and D-E respectively). It's a by-product of certain tunings.

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The symmetry of Dorian mode is also present in Pythagorean tuning (which goes very naturally with Wicky-Hayden), rather older than 12-edo! –  leftaroundabout May 26 at 20:11
Good point @leftaroundabout , I've edited my answer. –  cyco130 May 26 at 20:26

One could equally say that G#/Ab is also 'central'.I guess that looking at a keyboard,each is valid. But a violin, a guitar, a sax., a trumpet?

In written music, one could argue that D is in fact not central, as C takes that position, being in the exact middle of the treble and bass clefs.Symmetry is co-incidental, and not that important, otherwise all girls would be called Hannah and boys Bob!

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Good question. I've wondered about this before too. For example, in my answer to this question I used D as my central note in the table, because its half way between the sharp keys and the flat keys. Similarly, the Dorian scale is symmetric so that it is its own inversion -- sort of a musical palindrome (WHWWWHW). Also Sir Issac Newton recognized this symmetry: when comparing the color wheel to a musical scale, he started with red at D.

As for why this symmetry isn't more generally significant, I'm not sure there's really a good answer, unless it has to do with music in general eschewing symmetry. These asymmetries give the scale directionality and purpose. For example the half-step between the leading tone and the tonic gives rise to the whole idea of tonality, and dominants resolving to tonic.

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Here's my two cents (the way I've justified this to myself at least)

Let's look at the A minor pentatonic scale, which is symmetric: A C D E G. (intervals 3,2,2,3 semitones.) Now another way building it up from fifths: C G D A E. Indeed either way it looks like D is the central note.

Now let's look at this scale harmonically. We have four fifths, two minor thirds, and one major third, C-E.

With this major third, we can construct a total of two triads: C major C E G and its relative minor, A minor A C E. These are the only fully consonant triads available in this scale.

So the most fundamentally harmonic thing about this set of notes is the pair C-E. Now we normally name an interval by the lower note, as it is the more fundamental. Hence the note that most stands out in this group of notes is the C. So we can reorder to get C D E G A, known as C pentatonic major, or (uniquely out of the five possibilities) simply C pentatonic.

The same applies for the diatonic scale of Am/Cmaj (or simply C). We ad one extra fifth at the beginning and the end and get the following portion of the cycle of fifths: (F) C G D A E (B). Now we have three major thirds, which enables us to build three relative major/relative minor chord pairs: Fmaj/Dm, Cmaj/Am and Gmaj/Em. But again, the most central of these is the major third C-E.

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would this concept work if one took, say, Ab min.pent, or Bb min. pent. ? They will still be symmetric ? The intervals will remain the same, but they'll be centred somewhere else. It's interesting that the cycle of 4ths/5ths can be wheedled out of the pent., though. –  Tim May 27 at 5:11
@Tim Yes, the intervals are the same in all minor pentatonics. Ab minor is enharmonic to the more familiar scale G# minor (the relative minor of B major, whose "central major 3rd" is B-D#.) Bb minor is the relative minor of Db major, whose "central major 3rd" is Db-F. If you look at pythagorean tuning, you can see that the notes of both the pentatonic and diatonic can be picked out of a straight sequence of 5ths. It's what makes those scales so universal. The Wicky-Haden layout mentioned by the OP also makes this very apparent. –  steve verrill May 27 at 6:42
So, if it's all a moveable feast, how does D feature as the centre in any apart from Am pent.? –  Tim May 27 at 6:57
@Tim the Wicky-Haden layout, like the piano keyboard, is biased toward the natural notes (A minor / C Major.) I understood the OP's question as "if the piano keyboard and diatonic scale is symmetrical about D, why isn't D considered the most important natural note?" Or to put it another way "why isn't the Dorian, which is symmetrical, considered more important than major and minor?" Obviously if you change to a different key it will be symmetrical about a different note (always the root of the Dorian mode, a tone above the root of the major scale, or a fourth above the root of the minor.) –  steve verrill May 27 at 8:00

D is the most important note. Take a look at the Graduale Romanum (or any repository of Gregorian chant) and see how D dominates as the final. Look at the music from the middle ages, or of Machault, of Dunstable and Dufay - same story. But these last two started a trend to base harmony on triads, and they are either major or minor - and so they modes we know today as "major" and "minor" inexorably became central, and by about 1600 all other modes were considered "out" - at least as far as classical music is concerned; in folk music(s) D is still pretty important.

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D does play a central role in music theory, in the sense that it's the center of the Circle of Fifths which is intimately linked to key signatures.

... F♭ C♭ G♭ D♭ A♭ E♭ B♭ F C G D A E B F♯ C♯ G♯ D♯ A♯ E♯ B♯ ...

This is why the Wicki-Hayden keyboard (which features a chain of P5's along its /-diagonal) has D in the middle.

However, as you point out in your question, the central note D gets little emphasis in music theory. Rather, it's the seven notes in the center, forming the diatonic scale of “natural” notes, that are collectively emphasized.

On the piano keyboard, this emphasis physically takes the form of the separation between white and black keys. On the Wicki-Hayden keyboard, it takes the form of naturals being placed in the center of the keyboard while the black keys are relegated to the edges.

As for the lack of emphasis on D itself, this largely because modern Western music typically uses only two of the seven modes of the diatonic scale: Ionian (major, C-D-E-F-G-A-B-C) and Aeolian (natural minor, A-B-C-D-E-F-G-A), leaving other modes, including Dorian (D-E-F-G-A-B-C-D) neglected. Why this is the case is the topic for another question.

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