Now we have looked at the basics of chords and chord progressions, it's time to start looking at how they are used in action - how to harmonise a melody.
This lesson teaches you how to answer Question 1(a) in the ABRSM grade six music theory exam paper.
Here's a short melody in C minor (based on Bach's "Jesu, Jesu du bist mein"):
Your task, at grade six, is to indicate ONE chord at each of the places marked * to accompany the melody.
In this question, you don't have to do a full harmonization - PHEW! You don't have to write out each of the separate lines for alto, tenor and bass.
Instead, you have to suggest chords with inversions for each beat of a melody. (This is similar to the grade five question on cadences; it's a bit harder because it's longer, and you also have to say which inversion each chord is in.)
Write down your chords:
as Roman numerals,
with the small a, b or c to indicate the inversion
- that's all. (If you want, you can write all the actual chord notes on the staves, but we don't recommend this method.)
Harmonising a melody with Roman numerals is an optional question in grade 6 theory. If you prefer, you can create a bass line from a melody instead, using figured bass. We suggest you practise both questions at first, and then focus on the one you find easier.
So let's get started!
Each step is detailed with bullet points. An example for each step is given in a shaded box like this one.
Step 1: Key and Triads
Work out the key of the piece. (If you see accidentals making a sharpened leading note, it will be minor. If there are no accidentals, sing the melody through in your head and determine which note is the tonic.)
Write out and label all the triads for that key. This will help you avoid mistakes.
If it's in a minor key, don't forget to sharpen the leading note in triads V and vii; and you can safely ignore chord III - you don't need to use it in grade six.
Our question has three flats. It's C minor, because there is a B natural in there. Here are the triads in C minor:
Step 2: Identify Possible Chords
Use the table you wrote out at the beginning.
For each note marked *, write down the three possible chords it can be included in. (We'll choose the best chord later. For now, mark down all the possibilities.)
Note: we don't use chords with added 7ths at this stage in grade 6, so each chord is a basic triad.
In a minor key, the mediant, dominant and leading notes will only have 2 possible chords, not 3, because we avoid using chord III.
Here are the triads we could use with each of the notes in this melody. For example, the first G can be used with chords i, III or V. We don't use chord III at grade 6, so don't bother listing it!
You don't need to write any triads for the quaver D in bar 2 because it's a non-chord note.
Step 3: Do the Cadences
Remember that we find standard cadences at the end of a phrase or a piece. Because of this, when we harmonise a melody it's actually easier to start the end!
Check the end of the piece - if there is a double barline, it's finished. It will end on chord I (or i), and will be a perfect or plagal cadence.
If there isn't a double barline, it will probably be an imperfect cadence (ending on chord V).
Our melody does have a double barline at the end, so we can be sure it finishes on chord i. Cross out the other options for the last note.
Now look at the last but one note. This note forms part of the cadence. Which cadence should you use? Look at your options and choose the chord which forms part of a recognised cadence - perfect, plagal or imperfect.
We can choose from triads V, ii or vii. Only chord V is possible, making a perfect cadence. We now have the final two chords:
Check the middle of the piece - very often there will also be a cadence about half way through. You can spot a cadence because the music will pause momentarily and a longer note will be used (on a strong beat).
Look at your available chords, and choose the most likely cadence, using the same process as before.
The minim D in bar 2 is part of a cadence, so we'll choose chord V to make it an imperfect cadence.
The quaver Eb can be part of chord i or VI, and both of them are acceptable in an imperfect cadence. We'll pick chord i for now - but be prepared to change it later if necessary!
