I keep seeing around the place that chord names shouldn't describe the voicing of a chord, but simply the intervals. If this is the case, why do the intervals ♭13, ♯11 and ♯9 exist? Are they not just the equivalent of ♯5, ♭5 and ♭3?

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    You could help us help you by citing a reference to support your statement "I keep seeing around the place that chord names shouldn't describe the voicing of a chord, but simply the intervals". What does that even mean? Can you give us a book reference or even a website reference where this is stated? – ggcg May 22 at 14:56
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    The interval from 1 to 9 is much bigger than from 1 to 2. They are simply not the same interval. The fact that a 9th is an octave above the 2nd does mean that they share some similar qualities but the pair of notes played together (1, 2) and (1, 9) are different. – ggcg May 22 at 14:58
  • @ggcg Why then are open voicings of, say, simple triads, considered the same triads? It's a good question. Why can some chord tones be crammed in the same octave, but others can't. – piiperi Reinstate Monica May 22 at 18:00
  • Perhaps my comment is being taken out of context or does not address the question. In fact you can shuffle the notes in any order and you still have the same chord. It is a naming convention. – ggcg May 22 at 18:24

Names such as ♭13, ♯11, ♯9 indicate "extensions" of the chords, on top of the basic triad (or seventh, as the case may be)

So for example C7♯9 means that you have a basic major triad (C-E-G) and a dominant 7th (B♭). And on top of that, you have a ♯9, which is an octave above a ♯2, and that's a D♯. And that D♯ is marked as a ♯9, because D♯ is not there to play the role of a minor third, which would make the chord a minor chord, but is a "color note" on top of the dominant 7th chord.

One more thing to keep in mind: those extensions are usually voiced at the top of the chord. For example, in the "Hendrix chord", e.g. E7♯9, that ♯9 is always the highest note of the chord. If you played that ♯9 next to the major 3rd at the bottom of the chord, you'd get a super-dissonant clash between major 3rd and minor 3rd (i.e. augmented 2nd, i.e. ♯9) intervals. But if you leave the major 3rd at the bottom, and the ♯9 at the top, it sounds great.

You can make a similar analysis with all the other chord extensions you mentioned.

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    I often wonder whether Jimi (not the first to use it, by any means), knew what that chord was called, or considered it, like so many guitarists, as a 7th chord with m3 thrown in - somewhere. – Tim May 22 at 14:01
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    @Tim, believe it or not, I new about the dominant sharp nine before I new people called it the "Hendrix" chord! The name seems silly. It happens all the time in blues based stuff if you consider the basic dominant seventh plus the flat third in melody part. – Michael Curtis May 22 at 14:07
  • That's funny! It's a flat 3 in a melody line, but the chord must have a sharp 9! – Tim May 22 at 14:10
  • Didn‘t we have this discussion already with blue notes and bent tones? – Albrecht Hügli May 22 at 14:37
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    @Numpy, Chord spellings are a simplification, a shorthand system to show the most important information about a chord. Played in "root position" the basic triad and the seventh will fit in an octave, and additional extensions (9th, 11th, etc) in a second octave. But chords can also be played in different inversions (different note orders) and the positions of the various degrees can vary a lot. This all comes within the scope of a single chord name. You may say than more often than not, 9th, 11th, 13th are played above most other chord notes, but that's not a fixed rule at all. – MMazzon May 22 at 15:07

...why do the intervals b13, #11 and #9 exist? Are they not just the equivalent of #5, b5 and b3?

There are existing questions about this, but it may be hard for you to find them.

Intervals above the root higher than an octave (for practical purposed intervals bigger than a seventh) are called chord extensions. So, b13 #11 #9 are chord extensions, but #5 b5 b3 are not, because of size larger or smaller than an octave.

Side note, music theory distinguished between these interval categories as simple versus compound intervals. Ex, a simple interval is a major third, but adding an octave to it makes the compound interval of a major tenth.

When you have chord symbols with extensions/compound intervals - like G9 - by convention the chord is understood to contain a seventh. Written out explicitly the chord is G7(9). the 9 is an A natural over G7 which is G B D F.

If, that 9 was the simple interval 2, the chord is a basic Gmajor triad G B D with an added 2 and importantly no seventh! It's a Gadd2. That's mostly a theoretical example. Is more common to have a Gadd9 name. The add means add the interval - the ninth in this case - to a basic triad with no other assumed intervals. Gadd9 then is a major ninth added to a G major triad G B D A.

Finally, the big distinction between G9 and Gadd2, Gadd9 is G9 is a dominant chord but the add chords are not.

So, when b13 #11 #9 are used it means the base chords are seventh chords (and unless they are marked otherwise with min or something else the chords will be dominants.)

When simple intervals like #5 b5 b3 are used the chords aren't seventh chords.

One quibble is b3. Using that doesn't seem to be necessary, because you would just label the chord min. Gb3 would normally be written Gmin. If you wrote something like G7b3, it's confusing. Is it supposed to mean Gm7 or G7#9? If the meaning is to use a sharp ninth, then write that. I think most people like to include the seventh G7#9. If the naming system was very standardized you shouldn't need to write the 7, but the fact is the system isn't completely standardized.

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    Isn't Gadd2 normally Gadd9? Or do you see (hear) them as different chords? And I thought that anything over 7 had to include a 7 - of some sort. – Tim May 22 at 14:06
  • Yes, Gadd 9 to mean specifically add a ninth but not a seventh. Let me try to revise accordingly. – Michael Curtis May 22 at 14:09
  • Does it matter if the chord is a dominant that is resolving or an extended root chord of the tonic at the end? – Albrecht Hügli May 22 at 14:44

How could they possibly be? D4 isn't the same as M3, so what would make ♭13 the same as ♯5 (which should be augmented 5).

Maybe what's been missed is that there are at least two different names for any one sounding interval. For technical reasons.

But getting back to your ♯9, for example. It comes after the octave ( it's >8) so already in a ♯9 chord, there's 1,3,5,♭7. Let's put it into key: C E G B♭. Then on top, almost an octave above that E, there's D ♯. It might sound like E♭, but if your idea was employed, it would be played right next to the E. Try it and listen!

No, the numbers are larger than 8 because they are played above the basic triad plus root octave (if needed). Were they as you suggest, some of those chords would just sound muddy. On any instrument. Try it.

All that apart, chord tones normally work using the odd numbered notes (6ths aside!), so a convention already exists, and since most chords will have a 5 anyway, it is less confusing to not duplicate a note name.

And you're right - chord names don't reflect the voicings - not even slash chords (but maybe power chords..!)- but merely the note make up.

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  • Is the 13 not just the 6th interval an octave above? so a b13 is enharmonic with a #5? Also your last sentence is the source of my confusion - chord names DO reflect the voicings according to your very own answer, just not outside the next octave. If I played that #9 where the b3 is located it would sound terrible, but that's still just a voicing change. The notes themselves are enharmonic. So I guess the simple answer is yes - they reflect voicings up to the next octave only. – Numpy May 22 at 14:11
  • True, to a degree. Voicings are the order one plays notes in - inversions are close to voicings, but still don't exactly say which order: root C major will have C at the bottom, but the order of the E and G could be either way.With the 6th chord, I meant as a basic such as C6 - CEGA. Enharmonic gets in the way of a lot of interval understanding. So I guess the simple answer is yes - they reflect voices , but not necessarily voicings. Subtly (or not) different ! – Tim May 22 at 14:24
  • This is a bit off topic, but after researching the difference between D4 and M3 I just wanted to ask - what are the practical applications for distinguishing between these two interval names and potentially others? They seem to introduce more confusion when really the end goal is to just play the music. – Numpy May 22 at 14:29
  • @Numpy chords are built from 3rds, think of the Maj scale played every other note, 1, 3, 5, 7, 9, 11, 13... repeat. The chords and their extensions come right out of this pattern. The fact that 9 is the octave of the 2nd doesn't make the 2nd in this context. – ggcg May 22 at 14:30
  • @Tim, there are plenty of "muddy" voicing of these chords. – ggcg May 22 at 14:31

Chord symbols are a naming convention for describing chords that consist of stacks of thirds. As an exception to this basic form there are "add" chords where you simply add a note that comes from outside the stack of thirds. A more systematic name for a "6" chord would be "add6", but to keep it shorter it's called just "6". Another exception or modification to the basic form are "sus" chords which "suspend" the third by substituting it with another note. (think about suspenders! elastic strap pulling the chord's third to some direction)

Even though the higher-than-octave notes in the 9, 11 and 13 chords you're referring to could be mapped back to the first octave, they're looked at as stacks of thirds in the culture for which chord symbols were invented. There can be different voicings where some chord tones are spread to octaves (or duplicated) in various ways, but the normalized stereotypical form of a 9 chord is a stack of four thirds on top of each other. Not a "7add2". It's a cultural convention. (There are reasons and cultural history behind this convention though, it's not arbitrary)

If there was a musical culture that doesn't look at chords as stacks of thirds but by placing all notes in the same octave, then for that hypothetical culture, you would probably have different meanings and conventions for chord symbols.

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