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Figuring a Bass Line

In question 1 of the ABRSM Grade 7 music theory exam, you need to work out the figures which belong to the combined bass and soprano lines. A chord is needed at each asterisk, but the chord should be left blank if it’s a root position 5/3 chord which is not part of a cadential 6/4 and does not need any additional accidentals.

ABRSM Grade 7 music theory Q1 figuring a bass line

As well as testing your knowledge of the actual figures, these type of questions also test your ability to work out the key and any modulations, your knowledge of progressions and inversions, and of dissonance and its preparation and resolutions. You will also need to be able to differentiate chord notes from decoration notes.


Once you have determined the home key, in most cases a note which is raised from its current form with an accidental (e.g. F>F#, Eb>E or C#>C##) will be the leading note of a new key. (However, always check that any assumed modulation does work, by looking at the chords which follow. Usually the leading note moves to the tonic in chord I).

Modulations back to the home key will not necessarily need any accidentals, and modulations to the subdominant are sometimes difficult to spot for the same reason, so always check that the progressions make sense in the prevailing key.

Look at the cadence at the end of the phrase to be sure you are moving towards the correct key.

Related Keys

Music from this era (late Baroque/early Classical) usually moves to a closely related key, whether as a modulation, or just passing through.

The most closely related keys are the dominant and subdominant, and the relative major/minor.

It’s also worth remembering that the dominant chord is occasionally used in its minor form (parallel), in a minor key. For example, in A minor, we would normally expect the dominant chord to be E major, but you could equally use the dominant key of E minor at a modulation.

Progressions and Inversions

Remember that chord Ia is normally only ever approached by V, IV or vii°. Chord Ib can be approached by other chords, but like all first inversions, it is usually approached by step or third (not a 4th or 5th). Second inversions can only be used in specific places, and are also not normally approached by a leap.

Chords V7 and vii° normally move only to chord I. Chord V moves to I, or sometimes VI.

Don’t forget to raise the leading note with an accidental in the figure, in minor keys. (Except if the progression uses minor chord v. Minor chord v can only be used mid-phrase, never at a cadence, and never moving to chord i).


Dissonances are accented notes which are 4th, 7th or 9th above the bass note.

Normally, all dissonances are prepared in the previous chord, and resolved downwards by step in the following chord. 7ths may alternatively be approached by a leap up or a step down, instead of a preparation, but all other dissonances should have a proper preparation note.

Usually, it is enough to check the voice leading in the visible parts, but if you create a chord where, for example, the 7th would be an alto or tenor note, you will need to visualise whether the preparation/resolution will also work in that same part. 

Chord Notes and Decoration Notes

Every note (in the soprano and bass) needs to have a purpose (not just those aligned with the asterisks). Each note must either fit the chord you have chosen, or be a standard type of decoration, such as a passing or auxiliary note. The continuation lines show you how long each chord lasts for.


Work out the home key. (Each time you meet an accidental or note which does not fit the prevailing key, work out the new key).

Look at the bass and soprano notes that belong to the first indicated chord. Don’t forget to think about added 7ths/9ths and suspensions. Decide which (if any) are decoration notes and therefore which do not need to be in the chord.

Look at the previous chord and ensure that the progression is valid, moving into this chord.

Lightly pencil in the figure, including any necessary accidentals. Write down the Roman numeral and inversion as well as the figure (so that you can see the progressions (and keys) more easily. (You will need to erase the Roman numerals when you’ve finished).

Move on to the next chord. Check whether it makes a correct progression with the previous chord you just pencilled in (if not, reconsider the previous chord). If it seems ok, pencil it in lightly and move on to the next chord.

model answer