# What makes a chord a sus chord?

In light of some recent answers to questions I have asked on Stack Exchange with regards to naming chords, I have decided to refine things a little further, focusing on sus chords.

If a chord contains no 3rd, but does contain a second or fourth, then it can be considered a sus chord if the function of one of these extensions is to resolve to the 3rd of the chord. This makes a lot of sense, particularly when you consider the classical beginnings of the suspension (4-3, 9-8, 7-6).

However, I see examples of chords that contain the 7th and 4th, which have no intention of having their fourth note resolve down to the third, but are still considered sus chords. (A7 sus4 flat 9 being an example). Would this chord not be better described as some sort of A11 flat 9 for this reason? Otherwise, I am not really understanding what truly makes a chord a sus chord.

Thanks!

Ed

• Can you give an example of a song that uses A7sus4♭9? What function does it have? Feb 14 at 23:46
• hi phoog- its a dominant chord derived from the second mode of melodic minor. I have only seen it talked about on tutorials/ videos, so cant give an example. but I think the idea is you can use it as a substitute for V7. Feb 21 at 16:00
• ...as a substitute for V7 of what key? Feb 22 at 8:01
• D. I'd imagine you could also use it as the ii chord (or V/V) to D7. ii coming from the second mode of melodic minor, and D7 coming from the fifth mode. Feb 28 at 15:16

Strictly speaking, sus is only replacing the 3rd with a 4th. Often, the term sus is also used for replacing it with a 2nd, although that ought to be called a retardation. I imagine originally it was only when the sus was to return to the basic chord, but as times move on, it now applies to any chord where 3 has been thrown out in favour of 4. But, yes, most times it still applies.

In my world, a sus chord which contains the 3rd isn't! An 11th chord, for example, theoretically comprises 1,3,5,7,9 and 11. Often, the 9 is omitted, keeping the 7th (of some variety, usually m7) in, and voicing the 4th not as a 4th, but as an11th. And certainly not replacing the chord's 3rd!

Sometimes a point is reached where it's virtually impractical to sensibly name a particularly complex chord. That point is reached in your last example. A7sus4♭9 will not contain the 3rd - C♯. Otherwise it's not a sus. It may end up being A11(♭9)(no 3) though. A11♭9 will include C♯ (and the D note). That way, the name includes all the relevant details - and notes.

• Thanks Tim- this is bang on my thinking. I even saw Rick Beato describe an Am7sus4flat9, which makes even less sense, as the third is there from the beginning! Feb 14 at 17:37

I think we often find misuses of the terms in music. Sus chords will not contain the 3rd. All other extensions do contain the third. An 11th or 13th or 9th chord by definition will contain the third and one often sees voicings that will sacrifice most other notes to save the third. A common 13th chord voicing on the guitar just has (1, b7, 3, 13) and no 5, 9 or 11 even though they are in the spelling of the chord. You bring up a very interesting point in that the function of the X sus(4) is a suspended resolution to X maj, and an x sus(2) suspended resolution to x min, but I don't think that function must be realized to preserve the naming convention of the chord. I've seen pieces that end on the I sus rather than I, just to leave the listener "unsatisfied" as an artistic decision. In modern music, especially rock, sus chords are sometimes used as is as the primary chords in a song without even moving the sus to the 3rd. But I would say that the naming convention should be preserved.

• thanks for your great answer. I'd just be interested to know how you would then distinguish between an A7 sus 4 and an A11 (no 3)? Feb 21 at 15:59
• Great answer, +1. Hit the nail on the head, IMO. @EdB123, A11(no3) isn't something we see in jazz (and I would think popular music, too). Mar 20 at 0:38

"sus" used to mean there was a 4th, but no 3rd. The current interpretation seems to be that you replace the 3rd with whatever follows sus, even though this leads to some quesitonable results (for example, a "sus2" chord is identical to a second inversion sus, and a "sus6" is identical to a first inversion minor triad!).

These labels grate on me, since their use is widespread I'm just tilting at windmills if I argue with them.

If you're seeing a ton of sus7 chords in a piece, it's likely that it's using "quartal harmony", which builds chords in fourths - the basic triad in quartal harmony is 1-4-b7, voiced without a fifth.

• I think your assumed definition is not quite correct. It didn't used to mean "there was a 4th, but no 3rd." More specifically it refers to suspending a resolution. Resolving to a major chord usually has the 4th moving to the 3rd a 1/2 step down. In a minor key you have the 2nd moving up to the b3rd a half step up.
– user50691
Mar 20 at 3:04
• I don't know why you would call it questionable - what's wrong with having different chords that are inversions of one another? "sus6", though, that one's pretty questionable... Mar 20 at 5:15
• @user45266 - it's possible Tom meant something like Csus4 contains the same notes (is an inversion of) Fsus2.
– Tim
Mar 20 at 7:27
• @Tim - Yes, that's almost certainly what Tom is referring to, I daresay. So what would be the issue with this sus2 chord? There are other chords that do the same thing: C6 and Am7, Dm7 and B half-diminished seventh, for example. And what would be a better name for the chord [CDG] on a C root? Mar 20 at 8:21
• CDG has become known as Csus2 - even though it's really a retardation. So Cret2 should be its name! Fsus4/C sounds fussy. Or even C2. It's interesting that sus chords don't have to resolve, bit like V/V doesn't have to be followed by V.
– Tim
Mar 20 at 8:26

However, I see examples of chords that contain the 7th and 4th, which have no intention of having their fourth note resolve down to the third, but are still considered sus chords.

The point is, I think, that even though the sus4 chord arose from voice leading and counterpoint, the designation has been used to describe the shape of the chord independently of the function.

The difference between a sus4 and an 11 is that an 11 could (should?) contain both the third and the fourth, while the sus4 should not include the third. Don't forget that the 4/3 chord was common even in baroque times because it is the second inversion of a seventh chord. Of course, that chord has a sixth rather than a fifth.

In general, the idea that chords are built by stacking thirds starts to break down when you start talking about pitches that have to be omitted from your stack of thirds in order to make a useful chord out of it.

In other answers there is some discussion of 4/2 chords (or 11/9 chords, perhaps). this shape can arise as a double suspension, as is relevant to this discussion, or as the third inversion of a seventh chord. Should we differentiate those functions in lead-sheet notation? Perhaps so, but I suspect that the answer is probably "no."

• hi phoog- thanks for the answer. Yes, I understand and agree that the main difference between sus4 and 11 is the third. However I see, for example, chords such as A11 (no 3). Could you perhaps explain to me why this chord would not have been described as a sus chord instead? thanks again for your input. Feb 21 at 16:05
• @EdB123 "Could you perhaps explain to me why this chord would not have been described as a sus chord instead?" I'm afraid I can't. Without knowing who described it as such or being able to ask why, my first hypothesis is that the people so describing the chord don't know what they're talking about. Feb 22 at 8:06

In rock and jazz the sus simply is not a bona fide suspension.

The term "suspension" is borrowed from counterpoint where the device is three events: preparation, suspension, and resolution. From a harmony perspective you have two chords.

Rock and jazz doesn't necessarily have that three event two chord device. A sus chord just replaces the third with a 2nd or a 4th. If sus2 or sus4 aren't specified and only sus is given, consider it a sus4.

it can be considered a sus chord if the function of one of these extensions is to resolve to the 3rd of the chord.

That would make it a suspension in the contrapuntal sense, or an appoggiatura, but in rock and jazz it is not necessarily that meaning. If you were to see Dsus4 you play D G A, if you see G7sus4 you play G C D F, regardless of what comes before or after.

Would this chord not be better described as some sort of A11

Some would say that chord should be written as G11 to show the C is a chord tone rather than a suspension which technically is a non-chord tone. The counter argument is whether the third is included in the supposed G11. If the third is not suspended, then it should be present along with the 11th. But that's just a theoretical point to reconcile jazz chord symbols with "classical" theory. It doesn't reflect rock and jazz convention. A sus4 is a perfect fourth and a perfect fifth above a root. 7sus4 or 11 signals voicings of stacked fourths or their inversions.

You can say rock and jazz misappropriate the term "suspension" from counterpoint, but it doesn't matter. These are just labels for certain chord types. It doesn't mean a contrapuntal suspension.

• great answer michael. in this case, I'm curious to know how you would distinguish between, for example, an A7 sus 4, and an A11 (no 3)? Would you say that these chords can be called either? Also, when you say 'a sus4 is a perfect fourth and perfect 5th above a root'- are you also including compound perfect fourths? or are you suggesting that the register of the 4th can indicate whether it is a sus or an 11? thanks! Feb 21 at 15:54
• @EdB123 the technical answer is A11 is not a sus chord. The full chord is root 3rd 5th 7th 9th 11th. Minimally it should have the root, third, eleventh and to make clear the eleventh is truly an extension above the octave the seventh is usually included. That leaves the ninth as a possible omission. The idea is a real 11 chord should be the tertian stack R 3 5 7 9 11, but in tonal harmony that chord isn't really used. Feb 22 at 18:36
• In tonal harmony, real chord tones only go up to the ninth. In a way this makes sense, because the 4/11 - call it FA in solfege - is a tendency tone, it's heard as not belonging to the chord. For all practical purposes when 7sus4 and 11 labels are used interchangeably, people are not making a true distinction between a suspension and a tertian extension up to the eleventh. The two chord symbols just amount to a sort of vague indication of quartal harmony, chords built in fourths. Feb 22 at 18:36
• thanks yet again for your explanation. So I suppose, with this being said, A11 (no 3) can't really exist, and only exists as a mis-spelling of a 7sus4 chord? Feb 28 at 11:24