Decide which chord to use

Question

I am trying to teach myself to create music. I know it is not a learned behavior and is rather a skill dependent process, but the basics have to be learned and that is where I am stuck. I play some piano, beginner level and has some knowledge of Indian classical music - Carnatic.

What I am finding difficult is to choose which chord to use at a specific part of the melody. When I attempt to play melody with a violin and add piano chords in the background (for example) there are a plethora of options before me. It is not practical to play every one of them and decide which one to choose and I may not be able to remember how all the chords sound. Is the decision of chord taken based on some rules, or is it based on the skill of the song writer? If yes, what forms the basis for such a skill?

Answer 1

One helpful starting point, though you may need to gather some further information to fully comprehend and apply:

Within a given key, all notes of the scale can be harmonized by one of three chords while giving a functional harmony. These 3 chords would be the I, IV and V chords of the scale.

We can use C Major as an example:

C Major Scale: C, D, E, F, G, A, B

• I = C Major: C, E, G
• IV = F Major: F, A, C
• V = G Major: G, B, D

Each note of the scale is in at least one of the chords. This means that whatever melody you play, assuming it fits into a diatonic scale, can be harmonized by at least one of these chords. You will have to make choices when there are common tones between chords but this will significantly decrease the amount of experimenting necessary to decide which of your options is best suited.

Not all notes should be harmonized as a chord tone though. A lot of times you will have a melodic phrase with a handful of notes that will be harmonized with a single chord. You then have to choose which of the chords will properly harmonize the entire phrase, not just the individual notes.

This approach works but you might find the outcome boring. All of the chords will work and properly support your melody in a traditional way but there is very little textural change, which leads to a very narrow artistic/emotional expression. A next step could be to look into relative relationships, which can point out the similarities between two different chords. Though the two chords are different and have different textures, they can serve the same function. This will allow you to incorporate minor chords, which is a huge textural change from exclusively using major chords.

Eventually the melodies you are trying to harmonize may have notes beyond the diatonic scale. That would make the 3 chord approach less than effective. However, if you learn and practice the 3 chord approach, then you will have a good understanding of harmonizing and will likely find it much easier to pick a chord.

Answer 2

I disagree with your first statement, Rana. Music composition is indeed a learned behavior. Some people can grasp the fundamentals of composition easier than others, but a lot if not most people who write music put a lot of work into developing the ability to do so.

With that out of the way, there are indeed a plethora of options for choosing to harmonize a melody. The more that you know about music theory, the easier that picking these chords becomes. A good set of chords tends to compliment the melody while moving seamlessly to other chords.

A good thing for a beginning composer is to identify what key the piece that you're writing is in. After that, find out what are the 'safe' chords to use in that key. For a major key it will be:

I. Major

ii. Minor

iii. Minor

IV. Major

V. Major

vi. Minor

viio. Diminished

For example if you're in the key of Gmajor, it is safe to use Gmajor,Cmajor,Dmajor,Aminor,Bminor,Eminor,F#diminished.

This is a good way to get confident with adding chords and harmonies to your melodies. These are by no means the only chords that you could or should use, but they will be very helpful in the early stages. Learn scales, learn about key signatures, and chords. Really analyze the chords, how you want to harmonize the melody, and how often you want to change chords. If you're writing a piece in 4/4 try switching chords once every measure, or twice per measure and start off experimenting with the chord that is the root to the note that you're playing. If you're playing in Gmajor and your violin plays an A, play an Aminor, if that doesn't please you, then try a Dmajor, since A is the fifth note in that chord.

Composition is a learned behavior, the more that you do it, the better that you get at it. Do not be discouraged if your first dozen pieces are not good. Composing can be learned!

Answer 3

If this were my problem, and I was using an equal-tempered instrument like the piano to accompany Carnatic music, I'd keep it VERY simple. I would try to hear the final note (sa, I think it is called) of the rag and play that as an octave in the bass, then try to add very simple pitches over it, experimenting with the perfect fifth above sa, the perfect fourth above, and maybe the major second above.

So, if the singer is singing a rag whose final note is, say, C#, then play C# in octaves in the bass, experiment with G#, maybe F#, and even D#. Avoid all the other notes until that sounds OK, then maybe try dropping others in as "neighbors" to those notes.

Any use of full chords will probably clash, since the thirds will not match.

Answer 4

Since writing music is an art, there isn't a single answer to your question. The approaches that others have offered are sound. I myself have learned how to write chord progressions in a different way.

What I've done is taught myself to improvise on the piano. I'm not particularly great at it, but what it lets me do is quickly try chord progressions and how they sound. As a result, I've created a library in my head of what kinds of emotional impacts chords have and how they relate to each other.

Now that I've built up that library (and I'm always experimenting and building it more), when I write a song, my first question usually is not, "What chords would complement the melody the best?" but rather, "What chords best develop the emotion and texture I want to portray?" Sometimes, I even deliberately allow this progression to contradict the melody somewhat, which can have rich and surprising results.

Again, this isn't the only approach to writing chord. You might find others' answers more useful or come up with your own approach altogether.

Answer 5

If you are trying to find the chords to play a specific song (as opposed to playing/improvising a new melody), here is a much simpler approach. Given that I, IV and V chords often work for most melodies, it is far easier to apply this same idea in the following manner: play the root notes at 1, 3 or 5 note intervals BELOW each melodic note played on the main down beats. These three melodic-bass note intervals will work for a large majority of the time, particularly for simple songs. Most of all, you can use this simple scheme to identify the root notes by simply looking at and mirroring whatever note you’re playing on the right hand (with little or no mental effort).

To find the chord, play the bass note and the notes at 3 and 5 note intervals ABOVE the bass note (or 1-5-10). After playing three or four simple songs (e.g. traditional xmas carols), you’ll start to get the hang of it!