Harmonization of a Melody in Brief


Suppose you have a melody and you don’t have chords for it. Let’s say you have written a tune starting with melody, perhaps using your voice. You would like to play the tune with chords so you need to figure out appropriate chords. What chords would be most appropriate? How should you do this?

If you know your instrument and you have a good musical sense you might do it through intuition combined with trial and error. However there is a systematic process for doing this. Even if you have good musical intuition, knowing the process may show you overlooked possibilities. I’ll give an outline of this method below.

The formal study of musical harmony is difficult, and not readily available to many. Although a person could presumably profit from such a study, learning many more aspects of how to harmonize; it is probably overkill for someone wanting to do a decent job of harmonizing a tune, but is not going to write complex pieces of music. In addition, it pretty much requires that a person is a fluent reader of western notation, which in itself is a difficult thing to master.

However, I will attempt to give a brief but useful method in this document. It does assume that you have some knowledge of music theory. Not a lot of knowledge, mind you, but some basics. If you don’t have understanding of these you will be lost trying to understand the document.

Prerequisites to Understanding

The basic things you need to understand are:

  • melody
  • musical notes
  • intervals
  • keys, scales, modes
  • degrees of the scale
  • tonics, sub-dominants, dominants, …
  • harmonization of a scale
  • triadic chord types
  • tertian chord construction
  • harmonization of a scale
  • primary triadic chord types
  • secondary triadic chord types
  • seventh chords
  • metre, beats
  • strong and weak beats in a measure
  • musical progression of chords
  • chromatic, diatonic and pentatonic scales
  • major and minor scales
  • intervals
  • scale tonic
  • chord roots
  • chord formulae

This knowledge is available from many sources; in paper books, electronic books and on the internet through numerous web pages and videos. Unfortunately, a lot of it is explained using musical notation, which is a study in itself. Until you know notation, it is hard to make sense of the explanations which use it. In any case, music theory is difficult enough regardless of notation. It is probably best learned with a keyboard in front of you.  At one time I stuck little letter names on my keyboard for each note. This works, although eventually a keyboard player would need to go beyond that. Even a cheap low end or second hand keyboard is a good investment for this purpose, if you do not have one.

First steps

First, let’s assume you have a melody. You need to determine:

  • the notes of the melody
  • the key, scale and the mode of the melody
  • the notes in that key and their degrees in the scale
  • the tonic note of the melody
  • the notes that comprise the triadic chords in that key
  • any notes in the melody that depart from the notes of the key
  • any modulations to a new key
  • the metre of the tune
  • where the strong beats are in that metre
  • the association between beats and the melody

This is probably sufficient information to start with.

Essential to harmonization is creating a piece of music that is enjoyable for you and, it is to be hoped, enjoyable for others.

Two Key Considerations

In harmonization there are two key technical considerations. Firstly: support for a melody note by a chord which contains it. Secondly: the flow or progression of chords through the piece. The context of chords surrounding a given chord and the movement from one chord to another is fundamental.

For the first point, if my melody note for a piece in the key of C major is A, I can put the F major, A minor, or D minor chords under it. The F consists of the notes F, A, C. The A minor consists of A, C, E. The D minor consists of D, F, A. Each contains the note A, so may be used.

So the first rule is that a melody note can rest on top of a chord quite nicely if that chord contains the melody note. The triadic chords contain three notes each and there are seven of them. There are three primary chords which are called major chords, and four secondary musical chords which are minor but one of them is also diminished.

For the second point, if I end up with the chords C major, A minor, D minor, G major, C major in progression, I have a conventional but strong sequence of chords. Any chord can move to any other within a given key, but some combinations will sound better; more interesting, and more pleasing. This is all a matter of taste of course, based on previous experience, with maybe some underlying physics and neuropsychology.

Scale Notes and Chords

The notes of the scale are numbered one through seven. Each of these notes in the scale is associated with a numerical value and a chord. This is shown in the following table for triadic and seventh chords, with examples for the key of C Major.

Scale Degree1234567
Example NoteCDEFGAB
Chord TypeMajorMinorMinorMajorMajorMinorDiminished
ChordI Majii minii minIV MajV Majvi minvi dim
Chord TypeMajor 7Minor 7Minor 7Major 7Dominant 7Minor 7min7 b5
ChordI Majii minii minIV MajV Majvi minvi min7 b5
ExampleCMaj7Dmin7Emin7FMaj7G7Ami7B min7 b5

Frequency of Chord Changes

When harmonizing a melody you can probably start by only harmonizing on the beats. You could decide to harmonize all beats but perhaps you could start by restricting chord changes to the strong beats. You may go farther and restrict that just to the first beat. It’ll be up to you decide what sounds best.

You can ignore melody notes that are not on the beat. If you tried to harmonize every note, things would get very messy, and quite often unmusical.

Note that in double and triple metre, the first beat is the strong one. In quadruple metre, the first and third beats are the strong ones. In sextuple metre, the first and third beats are the strongest. In all metres, the first beat is the strongest.

The Notes in a Chord

Below is a chart showing melody notes and triads in the key of C major. This understanding should become engrained for the chords in the keys you want to work in for easier harmonization. It is like learning the multiplication tables, but to my mind harder. I still have to think hard about it for any key but C.

Melody Note C D EF G A B
C MajPrimaryC   E  G    
D minSecondary  D  F   A  
E minSecondary    E  G   B
F MajPrimaryC    F   A  
G MajPrimary  D    G   B
A minSecondaryC   E    A  
B dimSecondary  D  F     B
C Maj 7PrimaryC   E  G   B
D min 7SecondaryC D  F   A  
E min 7Secondary  D E  G   B
F Maj 7PrimaryC   EF   A  
G Dom 7Primary  D  F G   B
A min 7SecondaryC   E  G A  
B min7 b5Secondary  D  F   A B

Matching Chords to Melody Notes

For any given melody note, you will have a choice of three chords to use if using all the triads in the key. It is your decision as to which to use. Clearly this decision can be changed later if you don’t like it. Some sequences of chords are going to be more musically pleasing than others. You get to choose.

To simplify things you can just use the primary chords, that is, the major chords, to do your harmonization. This will give you a harmonized melody. It may be very basic and maybe not interesting to you, but it’ll work.

If you choose to harmonize with all seven triadic chords you may be close to a finished product. This can be tweaked to your taste.

Notes to Chords in C Major

Below is an example, done without using notation, changing chords on the strong beats. The melody is childish, but good enough for my purposes. The possible triads are shown:

1C Em Am C F Dm C   
2Am C F Am Dm Bdim Am   
3F Am Dm F Bdim G F   

You can see that there are numerous ways to navigate the chords in this grid. Which do you choose? Find one that sounds good, and use it. It would take some time to try them all by the way; there are 2,187 possible paths, if I have calculated correctly.

Example of Harmonization with Primary Chords

Here is a possibility using only primary chords, though not the only possible one using primary chords:

1C C F C F G C   

Example of Harmonization with Secondary Chords

Here is another, using only secondary chords, again only one possibility:

1Am Em Dm Am Bdim Dm Am   

Note: A diminished chord is not particularly inspiring, but if you put a B diminished over a G bass note, it becomes a G Dominant 7 chord, which is far more useful, especially if followed by a C Major.

Example of Harmonization with All Triads

Here is a possibility using a mix of primary and secondary chords:

1C Em Am F Dm G C   

Using Seventh Chords

There are other possibilities for harmonization. One is to use seventh chords instead of triadic chords. These contain four notes. You can if you wish take that extra note in a seventh chord and use that as the basis for matching with the melody note. This may give you results you like. If not, don’t do it that way.

After having used harmonization with triadic chords you can also convert the triadic chords to seventh chords. Quite often the fifth chord in the scale is converted to a dominant seventh, particularly if it’s going to be followed by the first chord in the scale. You can experiment.

Here is an example, where on the 3rd measure, 3rd beat I use an E minor7 chord, since it has a stronger transition to the A minor chord. In the 3rd measure, 1st beat I use a B minor 7 flat 5 chord, otherwise known as a half-diminished chord. It is a more interesting chord than the B diminished.

1Am Em Dm Am Bmi 7b5 Em7 Am   

Going Further

There are many other varieties of chords that you can use. Once you have a fundamental harmonization done with triads you should look at other types of chords. These would include suspended 2nd and suspended 4th chords, temporary dominant chords, add chords, altered chords, poly chords, extended chords, and chords borrowed from closely related keys.

Notes Outside of the Key

I mentioned above that sometimes you find notes that are in the melody but not in the key. If these are on a beat, particularly on a strong beat, you can use these notes to make a chord by combining them with notes from the scale. This will probably sound fine although you might have to experiment to get the right chord.

Note that neither D Major nor B flat minor 7 flat 5 are in the original key, and the F# melody note is not in the original key either. This brief change in the note and the chord is called a change of tonicity.

1C   Am   D   Bm7   

Modulation to Another Key

A piece might actually exist in more than one key. One section may be in a first key and another in a second key. Treat these as two melodies and harmonize separately.

Bass Lines

You can add more interest to your progression by changing the bass line. The first method is through the inversion of chords, that is, taking a note that is not the root of the chord and making it the lowest note. The second method is to put a note in the bass of the chord that is not from that chord. This changes the chord type, and it may give it an entirely different name in another context. The third method is to add bass notes between the chords, to create what is often called a bass run. These can be notes from the scale of the piece, or chromatic notes. You might add chords to some weaker beats in order to get a more interesting bass line.

In Conclusion

This is pretty much a guerrilla treatment of harmony. It will get you started if you understand it, and will probably take you quite a distance. If you want to really see a deeper level of discussion, you will have to make a more formal study of harmony.

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