Musical Composition, Theory and Songwriting/naming root chords and inversions


QUESTION: Hello Dr Colin,
How can g sus4 and csus2 have the same notes different names.This would make is so confusing to spot a note and figure out what to call it especially with so many inversion possibilities. Must a midi composer concern them selves with this?


ANSWER: Hi Omer,

Thanks very much for your email. I am not sure whether I have fully understood the question but it's the end of the week so that might account for it.

(1) The actual notes of Gsus 4 are G, C, and D and
(2) The notes of Csus 2 are C, G and D.

On the face of it they look the same but the fundamental difference is that in the first one the bass note is G and in the second one the bass note is C. These two chord are very different in the way they behave.

As you know the abbreviation "sus" stands for "suspended". In the case of G sus 4 the 4th (the note "C") is suspended from the previous chord, whatever that happens to be. Suspensions create a discord which has to be resolved and in the case of G sus 4, the discord is created by the "C" and the "D". This is nearly always resolved by dropping the C to a B, probably in the following chord. A typical example of this effect in a chord progression in G major would be:


What happens is that the note C of the C chord is held over into the G sus4 chord and resolved in the G chord. However, this progression is a bit weak and you could make it more interesting by changing the last chord to Bm, like this:


The note C still resolves downwards which is what the ear seems to need.

Now in Csus2 chord the 2nd (the note "D") is suspended from the previous chord, whatever that happens to be. Historically, composers like it to resolve downwards to a "C" which of course is already in the chord as the bass note. As a result, this sounds a bit weak. You could easily resolve is upwards to an "E" thus adding the much-needed third of the chord. Here's an very simple example progression in C major:


Again, you can change the final chord (for example) to an Am which would give it more interest.

I agree that it can be very confusing but the fact is that the guitar chord system of notation (such as we have used here) is very imprecise and can be open to different interpretations. There is no particular need to get too involved in all this because the final result is what matters.

Incidentally, the technical terms for these are a "4-3 suspension" and a "9-8 suspension" respectively.

Anyway, I hope this helps a bit.

All good wishes


---------- FOLLOW-UP ----------

QUESTION: Dear Dr. Colin,

Thanks much for taking the time to explain Sus chords.  I see how the suspended has its origins from the previous chord along with it's resolution points.  

The answer however raises a few more questions.... one is how you have a D chord in a C major key and the other why call these "4-3" and "9-8" i see absolutely no connection with the Sus4 or the 2 in Sus2.  Am i missing something in theory?

Best Wishes

Hi Omer,

In the key of C major (for example) you can build a chord on any one of the notes of the scale. So without using any other sharps or flats the chords would go C-Dm-Em-F-G-Am-Bdim-C. You can try this on a keyboard by just playing the triad of C (i.e. the root C, the third E and the fifth G) and then just moving your hand up the scale. Sometimes the chord of D major can appear in a C major piece, because the music is temporarily changing key - a process known as modulation. This happens quite frequently in classical music and also (but to a lesser degree) in popular songs. However, we'd still say that the piece is in C major, even if there are brief excursions to another key.

To move to your second question, the numbers refer to the distance between the bass note and the note which is being suspended. It's actually a kind of shorthand which dates from the 17th century. In the "4-3" suspension, the "4" refers to the fourth note above the bass. Imagine a G chord with a G in the bass. The fourth above the bass is a "C" and in this suspension it resolves to the "B" below it. The "B" is a third above the bass note. This is where the "4-3" comes from. The expression Gsus4 tells us much the same thing but doesn't actually tell us specifically that the 4th resolves to a 3rd.

The same applies to the 9-8 suspension. Let's stay in G since we're already there. The ninth above the bass G is an "A" and as I said before it traditionally resolves down to a G which is an octave above the bass G - hence the figure 8. In guitar notation it would be described as Gsus2. This actually means the same thing because a 2nd above G is also "A". It is just two different ways of expressing the same idea.

The important difference is that unlike (for example) Gsus4 the expressions 4-3 or 9-8 (and there are others) can be used in any key and mean the same thing although the actual notes will be different.

It's quite difficult to explain (and understand) this from a written explanation and makes much more sense using a keyboard. There's a YouTube video that you may find helpful.

I don't know your present level of musical knowledge so I apologise in advance if the video is too simple. But you could well find other videos on YouTube that explore these issues that interest you.

I hope this helps.

Best wishes


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Dr Colin


I can answer questions from students of "classical" composing, arranging, notation problems and music theory, writing for instruments and voice and writing music for education. I can answer questions about orchestration but I do not cover questions about pop or rock music, pop song writing or electronic music.

I taught for many years in UK up to "A" level theory and composition. I have spent many years in music education, initially (like everyone else) as a teacher. Then I moved on to advisory work (teaching teachers!) and also lectured, giving many workshops for teachers in developing music education skills and techniques. For a time I worked as a teacher-lecturer at London University's Institute of Education and eventually worked full-time as a Music Education Adviser to schools in part of London, offering advice on music education and curriculum development.


I started composing music at the age 14 (it was mostly rubbish, since you asked) and now have a large number of compositions to credit as well as many publications, especially for instrumental music and choral music. I have also written several acclaimed works for large orchestra and choir. My work has been published particularly in the UK (under different names)(notably by Boosey & Hawkes, Novello, and Schott) but also in the USA and the Netherlands.

My music for elementary players (several publications) has been performed and broadcast worldwide. I am now retired from my previous job as Music Education Adviser. These days I spend most of my time composing and arranging. I am currently working on instrumental arrangements of world national anthems for my National Anthems website and also completing a suite of very easy piano solos and duets for elementary players. For many years I have used the music program "Finale" for all my music writing activities.

International Society for Music Education; Fellow of the Royal Society of Arts.

"The Times" Educational Supplement; "Hi-Fi News and Record Review". For several years, I used to write for many of the state music education periodicals in the US and I also wrote several influential articles on instrumental music teaching for "Music Teacher" magazine in the UK. (UK).

PhD(Hons); MA(Hons); FLCM (compositon) ARCM, LMusTCL,(music diplomas)

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