I know there's an exception for "melodic minor" (M7 ascending, m7 descending), but does the framework of musical modes support the notion in general? Put another way, are there any modes that have multiple notes for a given degree regardless of the direction a player is going diatonically?
2 Answers
No
In the way the question is put, no. A mode containing, for example, both E♭ and E natural when ascending would consider those separate scale degrees and would number them accordingly.
Defining "mode"
Wikipedia provides a useful definition of mode:
In the theory of Western music, a mode is a type of musical scale coupled with a set of characteristic melodic and harmonic behaviors.
Diatonic modes
The diatonic modes all adhere to the rule that they have exactly one note per letter name, so for those modes, the multiple-notes-per-degree situation can't happen.
An exception (sort of): The "bebop" scale
The "bebop" scale is an eight-note scale containing both the minor and major sevenths above the tonic. The F bebop scale, for example, contains both E♭ and E-natural, and those are generally talked about as flat and natural (or minor and major) seventh degrees, respectively. For the purposes of this question, the bebop scale can be viewed as a "mode" insofar as it has a reasonably well defined melodic usage (though not harmonic), but in practice it's a modified mixolydian scale. Its typical usage is as a melodic path through a dominant seventh chord.
Direction-dependent notation
Melodic minor
Melodic minor, by the above definition, qualifies as a mode and therefore satisfies the question. It's the one mode/scale having distinct pitches ascending and descending.
It is not, however, generally thought of as a mode. It's more often just considered a variation of the diatonic minor (which is a mode), reflective of common compositional practice (leading tone when moving upward to the tonic; no leading tone when moving downward away from the tonic).
Octatonic (diminished) "modes"
The octatonic scale could be considered as having to "modes": the half-whole mode and the whole-half mode. The harmonic behavior of the octatonic scale isn't particularly defined (certainly not in the way the diatonic modes are defined), but they do vary from each other in their melodic characteristics. At that level, we might consider them "modes", and there are reasons they might be written using enharmonically equivalent notations depending on context (such as sharps when ascending and flats when descending). However, the pitches remain the same regardless; only their notation changes.
Whole-tone "modes"
The whole-tone scales do have a more defined (or at least, expected) usage, so could be "modes" in the sense given above. The whole-tone scales also might be written in enharmonically various ways as a matter of convenience. But they also would be equivalent in pitch, varying only in the notation used for those pitches.
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Fantastic answer, @Aaron, thank you. Follow up: in F bebop, would you notate an e minor chord as "viii" or does figured bass follow interval degrees from the root?– DexterJul 23, 2021 at 20:48
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1@DexterW The bebop scale is used in the context of diatonic chords, principally dominant sevenths. It's not a key in its own right, so one doesn't base chords off of it. Roman numeral analysis is really intended just for major and minor, while figured bass is a separate matter, just indicated intervals above a given bass note.– AaronJul 23, 2021 at 20:54
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2I'd tend to emphasize the first sentence of the answer, which is that this answer is actually required by the wording of the question. "Diatonically" tends to imply we're accepting all "legitimate" notes of a scale/mode are by definition part of a single scale, and other (chromatic) variants are "non-diatonic." In actual musical practice (as opposed to how scales are laid out in a theory textbook), many modes make use of chromatic variants that are really a part of the standard use of that mode and therefore might practically be thought of as variations of the same scale degree. Jul 23, 2021 at 21:01
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To elaborate on Athanansius' comment, it's useful to consider the minor mode as a single object (rather than 3 scale-based objects) with two mutable notes. Either form of these notes is "diatonic" from the point of view of the minor mode. It gets interesting when one looks at secondary dominants, Augmented Sixths, Neapolitan Sixths, and a few other chords; these contain chromatic notes but do not effect a change of key (or at least they can be used this way.) Not every music concept has a sharp boundary though they do have sharp cores. It's similar in other fields.– ttwJul 24, 2021 at 3:27
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@DexterW FYI, I've updated the info on the bebop scale. It is usually discussed in terms of two distinct seventh scale degrees that are both present ascending and descending.– AaronJul 24, 2021 at 3:38
Yes,
though this is matter of interpretation.
For example, in jazz terminology melodic minor denotes the following scale: 1 2 b3 4 5 6 7, regardless of the direction.
Seventh mode of melodic minor would be then: 1 b2 b3 b4 b5 b6 b7, however the most often it is thought of as: 1 b2 #2 3 b5 b6 b7. So rather than having minor third and diminished fourth, flat and augmented second (or ninth) coexist in the scale and the third is minor. The scale is also called superlocrian or altered and is a common choice to play over dominant chords with corresponding alterations.
This is a subject of interpretation, because it's up to you how you notate the notes, but using the scale in a way that the audience hears diminished fourth rather than major third is a nontrivial task.
If you explore modes of less commonly used scales, you will find more examples.
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@piiperiReinstateMonica I'm giving an example of superlocrian a.k.a. altered scale, which have both b2 and #2, so yes, you need to use accidentals to move back and forth between those two. Jul 24, 2021 at 17:19
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@piiperiReinstateMonica yes, I refer exclusively to western music practice. Considering what a person not previously exposed to western music tradition would hear, and how they would interpret it is highly speculative and doubtful. But still, in my answer I did write that it depends on interpretation. Twice. Next, the name melodic scale means a different thing in classical and jazz nomenclature, and I clearly indicated which meaning I use. I never suggested that it is an octatonic scale. Concerning your last sentence, it is not a mode of what? It's not a mode of ionian scale, I agree. Jul 24, 2021 at 19:16
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I was trying to say exactly that: in what you talk about, the scale degrees' mappings to notation depend on interpretation. But in the thing that the OP is talking about, there's no interpretation, the seventh degree is sometimes different. If scale degrees can be altered, it's not a mode. In your example, the scale degrees are: first, second, third, fourth, fifth, sixth, seventh, and each of those degrees is always the same pitch. In the OP's scale, a different pitch is sometimes played when thinking about the seventh degree. And that's why it's not a mode. Jul 24, 2021 at 19:37
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@piiperiReinstateMonica right, but sticking to my example superlocrian it is commonly interpreted as a scale that has both b2 and #2, these both tones coexist. These are notes given in the scale, you don't alter them, you don't need to choose between them. If we count the notes in the scale, #2 would be the third note, but it is interpreted as a raised 2nd degree. You can find many other examples, but I like superlocrian as it is commonly used this way, so it's not an academic example. Jul 24, 2021 at 19:54
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But that's thinking about the notes in terms of how they map over "normal" diatonic scales, in the same way as pentatonic scales can be thought of in terms of which notes they correspond to in a 7-note major or minor scale. But don't you agree that it's supposed to be OK to play both the "b2" and "#2" of superlocrian simultaneously, but in the up/down differing melodic minor you wouldn't use both versions of the 7th degree at the same time? Which is why it's a chromatic alteration of the seventh degree, and it's not a mode. I removed my comments, because long discussions are not allowed. Jul 24, 2021 at 20:38