When writing second parts for melodies, I've read that a good starting point can be to write something basically parallel either a 3rd above or a 3rd below.

In both major and minor keys, the 3rd below option seems to present the problem of it being likely that the harmony note will not be in the "implied" chord. So in the key of C major, if I harmonise the note C with the note A, then if the implied chord for the melody was C major, the A is not in the triad, so I'm kind of creating a Cmaj6 chord.

Likewise, in A minor, using F to harmonise the note A seems to create some kind of Amb6 chord.

What am I missing here please? Is it generally OK/common practice to use these 3rd below harmonies and simply hear them as "colour" against the implied triadic chords?

What about starting a 4th below instead - this would seem more logical as the 4th below gives the 5th of the implied chord. Is this a better/more common approach?

Any help much appreciated.

  • This is exactly why the rule of thumb states "a third below or above". Neither works for all notes in all melodies. You also need to exercise judgement from the get-go. Jul 9, 2022 at 13:10

3 Answers 3


What am I missing here please?

Often, if the chord is C, the melody will have E or G. In such cases, the third below is also a chord tone.

in the key of C major, if I harmonise the note C with the note A, then if the implied chord for the melody was C major, the A is not in the triad, so I'm kind of creating a Cmaj6 chord

But "if the implied chord for the melody was C major" is a big if. Not every occurrence of C in a C-major melody is harmonized with a C major chord. It could easily be A minor, F major, D minor seventh, D dominant seventh, or even A flat major or something else more chromatic.

The third above is probably more common because the melody usually ends on the root of the tonic chord, but even then if the harmony has been a parallel third below, one can break the parallelism and go to the fourth or sixth below. There's nothing saying that a parallel harmony has to be strictly parallel, and they often aren't.

What about starting a 4th below instead?

This could work, but parallel fourths give a very different feel from parallel thirds. Try it and see whether you like it! It may or may not be stylistically appropriate, depending on the style of music you're making.


Either a 3rd below or a 3rd above. But don't stick slavishly to one of those, use whichever is appropriate.

Yes, if the melody starts on the tonic, a 3rd below might sound odd. Better to choose a 3rd above (or a 6th below, which is the same thing).

If the melody lingers on the dominant note (and the harmony at that point is V) better choose the 3rd above. (But the harmony might be I, in which case... yes you've got it :-)

If you want a 'rule', we can go back to the old concept of 'avoid notes'. An added 2nd or 6th doesn't hurt and can add colour. But avoid harmony notes that are a semitone away from a chord note. If the chord is C major, obviously you can use the chord notes C, E and G. D and A are colourful but do little harm. But B (a semitone away from C) and F (a semitone away from E) will clash.

But... and it would be easy to go on. The maj7 is hardly considered dissonant these days. Other intervals can sound good. Not Bach chorale-style good perhaps, but still good. I transcribed some Everly Brothers recordings recently. Solid, respectable uncontroversial harmonies, yes? I was surprised to discover they sometimes harmonised with a string of consecutive 5ths!

However. Yes, 3rds above and 3rds below are good. But you probably won't get through a whole song without swapping between the two!

  • Thanks that's helpful. One of my use cases is recorders, where higher notes can dominate too much, so "rules" for harmonies below are of particular interest. Also, in Am, the 3rd below gives F, which is a minor 6th again the Am triad. This seems like it should be an "avoid," but I seem to remember it sounding OK. So "let your ears decide," I guess? Jul 9, 2022 at 18:10
  • F under A is quite a clash if the chord is Am. You could go Melodic Minor though. F# is pretty!
    – Laurence
    Jul 10, 2022 at 14:18

What am I missing here please?

You are able to figure out what the resulting chords are, no problem there. But you're supposed to listen to it and keep what you like. :) If you don't want to make the C chord a C6, then don't add an A vocal harmony, add something else.

There are basically two styles for creating backing vocal harmonies:

  • (A) Follow the steps of the melody along the scale, at a distance of a fixed interval. Change the interval if it's necessary for the chord you want to create, or keep a fixed interval if you like the way it sounds. Style A in its simplest mechanical form only needs to know the melody, a scale and a set of intervals.
  • (B) Do not follow the steps of the melody. Backing vocals sing chords like an organ chord or synth pad. Lead melody goes up and down, but backing vocals only change pitch when the backing chord changes. Style B needs information about backing chord changes.

Notation examples of the two. First, style A, lead melody in black, harmony notes in blue.

vocal harmony style A - intervals

Then style B, harmony notes shown in green.

vocal harmony style B - chord tones

Style B seems to be used more in rock music, and style A more in pop/jazz. In style B, sometimes the lead melody notes can even overlap with the backing voices, and when the lead melody steps up and down, there can be close intervals like seconds etc. In traditional classical styles this would probably have been frowned upon, but I think it can be a nice effect and is really a matter of taste.

There's also a combination of the two: sing tones of the written backing chords only, but move to a higher or lower chord tone, if the melody steps on your current note.

If you look at vocal harmonizer effect devices, they are divided in these two categories. There are scale-based harmonizers where you set a scale and supply the lead vocal into an audio input. And then there are chord-based harmonizers with a lead vocal input and a backing chords input, where you connect e.g. a guitar that plays chords. Some harmonizers have hybrid modes where you set a default scale (by specifying a key), but you can override or augment it by playing chords.

  • This is very helpful, and I will reflect on what you have written. I didn't even know vocal harmonizers existed, so that's certainly something to check out. One thing you wrote confuses me though: you said style B only needs to know the melody and scale, but you also described style B as changing pitch when the backing chord changes. So are you saying that it doesn't matter what the chords are, as long as the backing vocals change pitch somehow at the time a chord change happens, or something else? Jul 9, 2022 at 18:22
  • 1
    @RobinAndrews I had A and B the wrong way around in that sentence, I fixed the mistake now. :) Jul 9, 2022 at 18:40

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