How to Harmonize a Chorale in the Style of Bach

The composer Bach set the standard for four-part harmony writing that is still in use by music theory students today. A common theory assignment is to harmonize a chorale in the style of Bach. If you can adhere to the basic rules of part writing, harmonizing a Bach chorale will become a useful skill.

Difficulty: Moderately Challenging

Instructions

1. Study the collection of Bach chorales closely. These are a great textbook on harmony. Keep in mind, though, that at one point or another, Bach breaks all of the part-writing rules. He is entitled to do so, beginning music theory students are not.

2. Find the end of each phrase and mark them using the correct cord progressions. In Bach harmony style, phrases almost always end with a perfect or imperfect authentic cadence. A perfect cadence ends on the I chord and an imperfect ends on the V chord, both usually in root position. These types of progressions create a sense of completeness to each phrase.

3. Use primary chords prevalently in the rest of the chorale. Avoid using the iii chord at all costs as well as the IV/7 chord. These are very dissonant chords. Look at the melody note and determine how it will fall in the chord. It is best to double the root most often, then the fifth. Use every note in a chord. Never omit the third in a chord, but it is permissible to leave out the fifth if necessary.

4. Feel free to modulate chords whenever possible. Bach did this masterfully and it creates a much more interesting arrangement. Modulate to closely related keys, those that are no more than one sharp or flat away, and always begin and end the piece in the same key. Otherwise, use modulation with little limitations in each phrase.

5. Write in common chord progressions. For example, the circle progression is a good one to use that ends with a perfect cadence. Stronger chord progressions move the root in increments of fifths, such as I-V-I or ii-V-I as in the circle progression.

6. Double-check that you have laid out your chords correctly and logically. Factor in cadences at ends of phrases, modulations, chord progressions and make sure you haven't included any forbidden chords. Now you're ready to begin filling in the parts of the chorale.

7. Follow the rules of part writing when filling in the alto, tenor, and bass parts. These rules include, but are not limited to: contrary motion to the melody in the bass, limited movement in the inner alto and tenor parts, write the parts within typical vocal range for that part, avoid leaps of more than a fourth in the inner parts, avoid parallel fifths and octaves in two voice parts and leading notes must always resolve to the tonic note.

8. Add inessential notes to create more harmonic interest. The basic types of inessential notes are the passing note, the suspension and auxiliary notes. The inner parts use these most commonly, although Bach uses them in all voice parts.

[jallenjazz]

on 6/28/2009 2. Both perfect and imperfect authentic cadences go from V to I. The difference is that in perfect, the root is in the soprano voice. The type of cadence which you are thinking of (ending on V) is a half cadence.