Sus2 and Sus4: The Chords That Won't Pick a Side

Here is the one fact that makes the whole thing simple: in any ordinary major or minor chord, the note that decides the mood is the third. It is the middle note of the three, and it is the one that says bright or says dark. Take it out and put a neighbour in its place, and the chord can no longer make up its mind. That, and very little else, is what the word "suspended" means.

What you are actually doing

Sit at a keyboard, or picture one. A C major chord is C, E, G. The E in the middle is the third, the note doing the deciding. For a sus4, you slide that E up one step to F: now you have C, F, G. For a sus2, you slide it down instead, the other way, to D: C, D, G. In both, the third has gone missing. The chord keeps its outer notes, its root and its fifth, and swaps the deciding note for the one just above or just below.

Have a listen. Play C major, then Csus4, then back to C. You will hear the F lean against the chord and then drop home to the E, like a foot feeling for the next stair and finding it. Now try C, Csus2, C. Softer, more open, less of a lean and more of a held breath, but the same family of feeling: a note standing in for the third, waiting to be told where to go.

The reason it sounds unresolved is worth saying plainly. That fourth, the F, sits one step above the note the ear is quietly expecting. It is a small held tension, and tension wants to move. The well-behaved thing for it to do is to fall the single step down to the third, and when it does, the chord finally picks a side. The whole drama of a suspended chord is that one step, delayed.

Why it tends to fall home

A suspension is older than pop music by several centuries. The church composers used it as a way of making a line arrive late on purpose: hold a note from the chord before, let it clash for a beat against the chord that has arrived underneath it, then resolve it down. The ear leans in for that resolution every time. We are built to want the held note to come to rest.

So most of the time a sus chord is a guest, not a resident. It turns up on the way to somewhere, leans for a moment, and then the third arrives and settles the house. The cleverest thing in music is usually the simplest thing held a beat too long, and that is exactly what this is: an ordinary chord, with its decision postponed by one note for one moment.

The whole drama of a suspended chord is one step, delayed. Hold it, and the room leans in for the note that has not come yet.

When you leave it hanging on purpose

And then there is the other use, the one that makes these chords worth knowing rather than merely worth defining. Sometimes you do not resolve it. You let the sus sit, and sit, and never quite tell the listener which way it was going to go. A song that opens on a sus4 and lets it ring before anything else moves is buying itself a particular kind of hanging air: expectant, unsettled, a question with the answer kept back. A great deal of folk picking and a great deal of wide, ringing guitar music lives in exactly that suspended air, the third left out for whole bars at a time so the music keeps its open sky.

I was reminded of this the other Sunday. There is a session at a pub near me, the Hare, that has run in the back room for twenty-odd years, and I took along a reworked intro to an old standard that hangs on a suspended chord before the tune proper begins. On the page it had always closed up too fast. In the room, with everyone holding it, the tune breathed in a way it never had under my own hands at home. That is the thing about a sus: it is a chord that needs a little patience spent on it, by the player and the listener both.

How to meet it for yourself

Here is the smallest experiment that works. Take any chord you can play cleanly, and find its third, the mood note. Lift it one step. Listen. Drop it back. Listen again. Then try lowering it a step instead, into the sus2, and notice how much gentler that version is, how it opens rather than leans. You are training your ear to hear the third going missing, which is the whole skill here.

If you would rather hear the suspension cleanly before your fingers can shape it, the chord builder will sound out a C, a Csus4 and a Csus2 in any order you like and loop them until the difference is obvious. It sits naturally alongside the way one missing or altered note changes the whole weather of a chord, which is much the same idea I wrote about in what "diatonic" actually means, if you want to keep pulling the thread.

My old teacher Reuben used to say a suspended chord is a sentence with its last word held back: the longer you hold it, the more the room wants to finish it for you. So spend the tension deliberately. Let it lean when you want a pull toward home, and let it hang when you want the sky. Play the C, the Csus4 and the C back a few times tonight, slowly, and let your ear keep the shape of the lean. ...there.