So a friend of mine gave me a little musical phrase and I'm stumped as to what exactly I should do with it. Here's said phrase:

musical phrase

How do I find the implied key signature and the implied chord progression to accompany this phrase? This question isn't just for this phrase in particular but phrases in general, but some help for this one would be nice too!

  • That's a lot of theory in one question.
    – user50691
    Commented Nov 18, 2018 at 22:22

3 Answers 3


The answer to this sort of question is usually 'could be lots of things'. But in this particular example, there's a strong clue in that chromatic Bb, A, Ab, G line. That outlines a very common progression in Eb major. The shorter notes do nothing to contradict an Eb, F7, Bb7, Eb progression. So, for once, I think we can say there IS an obvious implied harmony!

So, what do you do next? I suggest that, having stated the obvious harmony, you then repeat the melody, or a variant of it, with a different harmony.

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  • Thank you! This is very helpful. Now if I am going to use this chord progression, what is the lowered third doing in the analysis? Do you have any tips for how I could work with it or what its potential role is? Is it like a modulation or what?
    – user54380
    Commented Nov 18, 2018 at 23:09
  • I can't see a lowered 3rd? If we're in Eb major, I can see a raised 4th, the A nat. There's no modulation. Play Bb, A, Ab, G melody against Bb, C, D, Eb bass line. Possibly the most clichéd cadence there is, apart from 'shave and a haircut...' en.wikipedia.org/wiki/Shave_and_a_Haircut
    – Laurence
    Commented Nov 18, 2018 at 23:54
  • Sorry, what I meant was the raised 4th. What exactly does that do to the composition?
    – user54380
    Commented Nov 19, 2018 at 0:08
  • It modifies a standard diatonic 'cycle of 5ths' sequence by being II7 rather than ii7. It's the 'dominant of the dominant'. So common as to be hardly worth a mention!
    – Laurence
    Commented Nov 19, 2018 at 2:21
  • Oh my god you're right. It's the dominant of the dominant! I feel so stupid. I've forgotten all my music theory knowledge. Thank you so much, I definitely feel more confident in using this now!
    – user54380
    Commented Nov 19, 2018 at 2:26

Assuming you know your keys, circle of 5ths and 4ths etc. You could start by looking at the simplest key that contains the accidentals in you phrase (not the only approach but hopefully a logical starting point).

The sequence of flats is (B, E, A, D, G, C, F) so the Key of Eb Major is possible.

Then ask yourself if the Melody seems for favor notes from the Eb chord (this is assuming that the composer intended to be on the I in the phrase, and this type of analysis requires assuming, then testing your assumptions, then changing your mind until your assumptions make musical sense. In time you get better and making good assumptions).

In my opinion the melody does not really look like an Eb centric melody. It looks more Ab centric. But this does not really mean that you are in Ab. You could assume the key is Ab with (B, E, A, D) flats. This does not contradict the information given. Then the natural chords may be the I (Ab), unless you are looking harmonize each note as in classical Homophony. But it could be that this phrase is in the key of Eb and centered around the IV chord (which would be the Ab).

Without any additional context you could go either way. Was this one phrase from a bigger piece or an original composition that you are trying to do something with? That would help us help you.

As for picking the correct chords to play with the phrase, that could go in a couple directions. If you want Homophony you need to identify a key choice then pick chords that contain the note in question and move gracefully form the chord before and to the chord after. There is a whole science behind this with rules and regulations (too much for a single post). If you just want to vamp behind the phrase and not be obtuse you can look for chords that contain the "featured" notes. In this case one choice is to drone on Ab. The notes that are not exactly in that triad (Ab, C, Eb) may still sound nice (being 9ths and Major 7ths), or act as passing tones. The Bb, for example could be harmonized by the V chord to create some movement.

I hope some of this helps but in fact you are asking for a lot given so little.

  • 1
    You feel the A natural inplies Ab major?
    – Laurence
    Commented Nov 18, 2018 at 22:54
  • That was not the intent. Oops. Your analysis is on the mark.
    – user50691
    Commented Nov 19, 2018 at 1:13

this small tune fits to the subdominant cadence: I - I7 - IV - IVm -> C C7 F Fm

try this on your guitar or piano

you can repeat this pattern and then continue whith a fourth higher e.g.

here you can download the berklee jazz book


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