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A10. Figured Bass Worked Example

Grade 6 Harmony Lesson A10 - Figured Bass a Worked Example

These are the steps you need to follow in order to realize a figured bass line. A worked example is explained in this lesson. Details can be found in the previous two lessons (see the lesson list at the side of this page).

Most theory students find that having a teacher to help with figured bass is essential. MyMusicTheory also offers a teacher-led harmony course which covers figured bass and harmonising a melody in a step-by-step way, with plenty of guided practice exercises. Please click here for more information about our tutored harmony course.

 

Figured Bass Method 

The suggested method for working through a question is this:

  1. Work out the key of the piece and make a note of which note is the leading note.
  2. Write the whole soprano line.
  3. Fill in the alto and tenor parts, chord by chord.
  4. Check for errors and rewrite where necessary.
  5. Repeat step 4.
  6. Add melodic decoration if necessary

In addition, you will probably find it easier if you follow these guidelines:

  • With every note you write down, check it with the previous note/chord for consecutives and augmented/diminished intervals.
  • With root position and first inversion chords (major and minor) always begin by trying to double the root. If you can't, try the fifth of the triad. If you can't either double the third or omit the fifth. 
  • Pay close attention to all "6" chords - some of them may be diminished, which means you have to double the bass note (third of the triad).
  • Try to sing through each individual voice part in your head. This is a quick way to identify augmented/diminished intervals.
  • Only add melodic decoration if your soprano line is tedious. It is not necessary if the melody line is sufficiently interesting.

Here is the bass line we are going to realize. There are many possible ways to answer this question - this lesson will look at just one.

figured-bass-worked-example-question

1. The accidental sharps in the figures, along with the final G, are clues that the key is G minor. This means the leading note is F# - be careful not to double this note.

2. Look at bar 1. The chords are G min (ib), D maj (Vc) and G min (ia). All of these chords contain a D, so D would be a poor choice for the melody to begin on (because we would end up repeating it in the next two or three chords!) Using contrary motion, we can make a mirror image of the bass line. Good soprano and bass lines often form mirror images, so aim to do it if you can.

bar-1-contrary-motion

In bar 2, although there is only one bass note, there are two chords to realise - first a 6-4 chord (G min), followed by a 5-3 (D maj). Again, both chords contain a D, so we'll avoid putting that in the soprano part, to avoid repetition. We've already used Bb and A in bar 1, so using G and F# in the melody here will make the soprano line a bit more interesting.

bar-2-two-chords

The leading note F# should be followed by the tonic G. After that, we could repeat the G (boring) or leap up to C. We can't fall to Eb, because it would create consecutive octaves with the bass. We'll follow the C with a Bb: again, we want to avoid those D's! Falling to G would make a rather bumpy melody line.

bar-3-leading-note-to-tonic

The last three chords form a cadential 6-4. We'll use Bb-A-B natural, because that allows us to write the alto part a third lower (G-F#-G) in close harmony. Don't forget to add the accidental natural to the last B!

bars-4-5-cadential-64

3. We now need to fill in the inner parts, checking each note as it goes down.

Place the alto and tenor notes of the first chord carefully. The soprano and alto should be relatively close together; the tenor and bass can be much wider apart. Double the root of the chord (as long as it is allowed!)

inner-parts-chord-1

Continue each chord by writing in the nearest possible allowed note. Use repeated notes if you can, if not then move by step. Double the root whenever you can.

inner-parts-bars-1-to-2

You can see that in bars 1-2 the alto part contains nothing but a repeated D. (Imagine if that was the soprano part!) The tenor part moves mostly by step. In the 6-4 chord the fifth is doubled (as per the rules), but in all the other chords it is the root which is doubled.

In bar 3, the alto leaps by a fourth to G - we could have used a step movement to Eb, but the resulting chord would be missing its fifth (G). We chose the leap, to achieve a fully sonorous C minor chord. In the last chord of bar 3, we doubled the third (Bb) in the melody line (see above), so we need the alto and the tenor to fill out the harmony with the root and fifth of the G minor chord.

inner-parts-bar-3

Finally, the cadential 6-4 at the end is completed by using the smoothest voice leading possible. In any cadential 6-4, the voices must always move to the nearest note (or not at all!).

innter-parts-cadential-64

Again, the repeated D's belong to one part only - this time the tenor voice. The alto takes the third below the soprano, in close harmony. Apart from the 6-4 chord, yet again the root is doubled in each chord.

6. The soprano line is actually fine in itself - it's not too repetitive and uses enough different notes. However, we'll add some melodic decoration anyway! Look for places where the melody moves by a third (for passing notes) or has a repeated note (for auxiliary notes). Check very carefully that writing the melodic decoration does not introduce any illegal consecutives into your answer! We can add two non-chord notes: in bar 1 (passing note) and in bar 3 (auxiliary note):

melodic-decoration

Checking your answer is absolutely vital. It's essential to check as you go along, but you also need to double check everything when you've finished. Be systematic in your checking, or you will overlook something!

 

Figured Bass Checks:

  1. Chord Notes. Check that every chord contains the right chord notes and that the note you have doubled is allowed. 
    Read each chord slowly and place a tick under it after it’s checked.
  2. Consecutives. Check each possible pairing of parts for consecutive octaves and fifths.
    Write out the following: S-A, S-T, S-B, A-T, A-B, T-B. Then follow each pair of parts, one at a time,  checking the intervals carefully. Tick off each pair of parts as it’s completed.
  3. Similar Disjunct Motion. Recheck the bass and soprano lines together. If both parts leap, make sure that they move in contrary motion.
    Look along the soprano and bass lines, following the contours of the parts.
  4. Voice Leading. Leading notes should resolve to the tonic in the soprano part (in A/T they may also move to the dominant), no illegal intervals, mostly stepwise movements. 
    Read each part separately. If you see large intervals or anything suspect, double check that it’s allowed. Sing through each part in your head.
  5. Cadences. Cadential 6-4s must move in the proper way, 6 moves to 5, and 4 moves to 3.
    Look at the figures. If you see 6-4 followed by 5-3, it’s a cadential 6-4. (If there is a 6-4 without the 5-3 after it, it’s a passing 6-4 and more flexible).
  6. Overlap. Make sure none of the parts overlap. 
    Check particularly between the alto and tenor parts, as this is where errors creep in.
  7. Diminished Chords. Diminished chords must have a doubled bass note.
    Look for first inversion ("6") chords and write out the letter names of the chord notes. If the chord is diminished, make sure the bass note is doubled elsewhere in the chord.

 

 

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