In this lesson we will focus on some particularly problematic areas of figuring a bass in Question 1 of the ABRSM Grade 7 Music Theory exam paper.
Accented Passing & Auxiliary Notes
Sometimes the melody note directly above the bass note is not actually a chord note, but instead it is an accented passing note or accented auxiliary note. Look at the shaded chord in this bar, for example:
If we assume that the melody note B is a chord note, we will need a chord with B and D, for example G major or B minor. G major would be in second inversion however, which is not possible here, so that leaves us with B minor in first inversion as the only possible chord.
However, notice the C natural; the accidental should alert you to the fact that the piece is modulating to G major. Remember that when a modulation occurs, the most likely chord is V7 in the new key, so we would expect a chord of D7 at this point.
Instead of using the melody note B as a chord note, we can treat it as an accented passing note, and focus on the C natural instead. This gives us two of the notes from V7a in the new key, figured with a 7 and a natural sign:
It can be tricky to spot places where an accented passing/auxiliary note occurs. Look out for key changes, and if you are ever stuck with a chord that does not seem to work, consider whether an accented passing note will fix the problem!
Decorative Notes in the Bass
Most of the time you only have one bass note to deal with. Sometimes however, the bass line is decorated, which you might find confusing. You might be wondering if you should count all the bass notes when working out the inversion, if the decoration includes chord notes. The answer is no. Only count the bass note directly above the asterisk.
The key is F major. In the shaded box, the bass note above the asterisk is Bb. The bass note A is an auxiliary note followed by another Bb chord note. But what is the function of the G? Because it is approached by a leap, we should consider G to be another chord note. The chord needs to include Bb, E and G, all of which belong to vii° in F major. However with Bb as the bass note the chord would be in second inversion, which is not recommended. These three notes also belong to chord V7 in F major, so here the best solution is V7d – figured with 4/2.
Be very careful to add in all necessary accidental signs to your figures. Accidentals in figured bass do not work in the same way as accidentals on the stave, in that they must be written each time they are needed within the same bar. (By contrast, accidentals on the stave continue to work until a bar line). But accidentals already used in a bar must still be cancelled within the same bar, if the same note is then used in an altered form.
Out of the following scenarios, points 3 and 4 are the trickiest to spot. With any bar which contains accidentals, analyse each chord carefully to make sure that the correct accidentals are present.
- Chord V in a minor key piece is normally a major chord > raise the third of the triad. (Minor chord v can only be used mid-phrase and is uncommon).
- An accidental given in the melody must still be shown in the figured bass.
- A previous accidental in the bass part or melody line might need to be cancelled further along the bar – check!
- A previous accidental in the figured bass might need to be cancelled further along the bar – check!
Here are some examples to illustrate:
1. The key is A minor. The shaded chord is the dominant, which should be E major. A sharp is needed in the figured bass:
2. The sharp in the melody line has to be shown in the figured bass:
3. The F# accidental in the bass line needs to be cancelled for chord iv, which is a D minor chord in A minor. (It was sharpened previously as an auxiliary note to prevent an augmented 2nd G#-F in the bass line).
4. The G was sharpened in the figured bass at the beginning of the bar for chord V, but the shaded chord is III, which would be augmented if it contained G#. The natural sign is needed to make the C major chord.